diff --git a/addons/account/security/account_security.xml b/addons/account/security/account_security.xml
index b0ca871d10c..6e6d9ce21ce 100644
--- a/addons/account/security/account_security.xml
+++ b/addons/account/security/account_security.xml
@@ -10,7 +10,6 @@
 
     <record id="group_account_user" model="res.groups">
         <field name="name">Show Full Accounting Features</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_account_manager" model="res.groups">
@@ -29,12 +28,10 @@
 
     <record id="group_warning_account" model="res.groups">
         <field name="name">A warning can be set on a partner (Account)</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_cash_rounding" model="res.groups">
         <field name="name">Allow the cash rounding management</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
 </data>
diff --git a/addons/analytic/security/analytic_security.xml b/addons/analytic/security/analytic_security.xml
index 5e66d317f5c..30f813f4a19 100644
--- a/addons/analytic/security/analytic_security.xml
+++ b/addons/analytic/security/analytic_security.xml
@@ -34,12 +34,10 @@
 
     <record id="group_analytic_accounting" model="res.groups">
         <field name="name">Analytic Accounting</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_analytic_tags" model="res.groups">
         <field name="name">Analytic Accounting Tags</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
 </data>
diff --git a/addons/crm/security/crm_security.xml b/addons/crm/security/crm_security.xml
index 83f3197a5b1..5a0fa127698 100644
--- a/addons/crm/security/crm_security.xml
+++ b/addons/crm/security/crm_security.xml
@@ -5,7 +5,6 @@
 
     <record id="group_use_lead" model="res.groups">
         <field name="name">Show Lead Menu</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record model="res.users" id="base.user_root">
diff --git a/addons/hr_attendance/security/hr_attendance_security.xml b/addons/hr_attendance/security/hr_attendance_security.xml
index 2f39cd13d21..6b903e890f9 100644
--- a/addons/hr_attendance/security/hr_attendance_security.xml
+++ b/addons/hr_attendance/security/hr_attendance_security.xml
@@ -34,7 +34,6 @@
 
     <record id="group_hr_attendance_use_pin" model="res.groups">
         <field name="name">Enable PIN use</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
         <field name="comment">The user will have to enter his PIN to check in and out manually at the company screen.</field>
     </record>
 
diff --git a/addons/mass_mailing/security/mass_mailing_security.xml b/addons/mass_mailing/security/mass_mailing_security.xml
index 823a9a4f4b5..308e02956ef 100644
--- a/addons/mass_mailing/security/mass_mailing_security.xml
+++ b/addons/mass_mailing/security/mass_mailing_security.xml
@@ -10,7 +10,6 @@
     <!-- Group to manage campaigns -->
     <record id="group_mass_mailing_campaign" model="res.groups">
         <field name="name">Manage Mass Mailing Campaigns</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <data noupdate="1">
diff --git a/addons/mrp/security/mrp_security.xml b/addons/mrp/security/mrp_security.xml
index 35d843b9aeb..d203cfc73c1 100644
--- a/addons/mrp/security/mrp_security.xml
+++ b/addons/mrp/security/mrp_security.xml
@@ -17,7 +17,6 @@
 
     <record id="group_mrp_routings" model="res.groups">
         <field name="name">Manage Work Order Operations</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
 </data>
diff --git a/addons/product/security/product_security.xml b/addons/product/security/product_security.xml
index 422d7ac75ec..08fec11f11c 100644
--- a/addons/product/security/product_security.xml
+++ b/addons/product/security/product_security.xml
@@ -4,27 +4,22 @@
 
     <record id="group_sale_pricelist" model="res.groups">
         <field name="name">Sales Pricelists</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_pricelist_item" model="res.groups">
         <field name="name">Manage Pricelist Items</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_product_pricelist" model="res.groups">
         <field name="name">Pricelists On Product</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_stock_packaging" model="res.groups">
         <field name="name">Manage Product Packaging</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_product_variant" model="res.groups">
         <field name="name">Manage Product Variants</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
 </data>
diff --git a/addons/project/security/project_security.xml b/addons/project/security/project_security.xml
index cfa175258f9..a34f32e7393 100644
--- a/addons/project/security/project_security.xml
+++ b/addons/project/security/project_security.xml
@@ -16,12 +16,10 @@
 
     <record id="group_subtask_project" model="res.groups">
         <field name="name">Use Subtasks</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_project_rating" model="res.groups">
         <field name="name">Use Rating on Project</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
 <data noupdate="1">
diff --git a/addons/purchase/security/purchase_security.xml b/addons/purchase/security/purchase_security.xml
index 75fbca272f6..b2d8e241ba7 100644
--- a/addons/purchase/security/purchase_security.xml
+++ b/addons/purchase/security/purchase_security.xml
@@ -17,12 +17,10 @@
 
     <record id="group_manage_vendor_price" model="res.groups">
         <field name="name">Manage Vendor Price</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_warning_purchase" model="res.groups">
         <field name="name">A warning can be set on a product or a customer (Purchase)</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
 </data>
diff --git a/addons/sale/security/sale_security.xml b/addons/sale/security/sale_security.xml
index 8936079df73..881b462b14e 100644
--- a/addons/sale/security/sale_security.xml
+++ b/addons/sale/security/sale_security.xml
@@ -3,23 +3,19 @@
 
     <record id="sale.group_sale_layout" model="res.groups">
         <field name="name">Personalize sales order and invoice report</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_delivery_invoice_address" model="res.groups">
         <field name="name">Addresses in Sales Orders</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_show_price_subtotal" model="res.groups">
         <field name="name">Tax display B2B</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
         <field name="comment">Show line subtotals without taxes (B2B)</field>
     </record>
 
     <record id="group_show_price_total" model="res.groups">
         <field name="name">Tax display B2C</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
         <field name="comment">Show line subtotals with taxes included (B2C)</field>
     </record>
 
@@ -37,17 +33,14 @@
 
     <record id="group_discount_per_so_line" model="res.groups">
         <field name="name">Discount on lines</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_warning_sale" model="res.groups">
         <field name="name">A warning can be set on a product or a customer (Sale)</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_proforma_sales" model="res.groups">
         <field name="name">Pro-forma Invoices</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record model="res.users" id="base.user_root">
diff --git a/addons/sale_stock/security/sale_stock_security.xml b/addons/sale_stock/security/sale_stock_security.xml
index 630a6512b2d..72c18b01594 100644
--- a/addons/sale_stock/security/sale_stock_security.xml
+++ b/addons/sale_stock/security/sale_stock_security.xml
@@ -3,12 +3,10 @@
     <data noupdate="0">    
         <record id="group_route_so_lines" model="res.groups">
             <field name="name">Enable Route on Sales Order Line</field>
-            <field name="category_id" ref="base.module_category_hidden"/>
-        </record>
+            </record>
 
         <record id="group_display_incoterm" model="res.groups">
             <field name="name">Display incoterms on Sales Order and related invoices</field>
-            <field name="category_id" ref="base.module_category_hidden"/>
-        </record>
+            </record>
     </data>
 </odoo>
diff --git a/addons/stock/security/stock_security.xml b/addons/stock/security/stock_security.xml
index 3301a5fbb8c..153b39dd9e4 100644
--- a/addons/stock/security/stock_security.xml
+++ b/addons/stock/security/stock_security.xml
@@ -4,12 +4,10 @@
 
     <record id="group_stock_multi_locations" model="res.groups">
         <field name="name">Manage Multiple Stock Locations</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_stock_multi_warehouses" model="res.groups">
         <field name="name">Manage Multiple Warehouses</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_stock_user" model="res.groups">
@@ -26,27 +24,22 @@
 
     <record id="group_production_lot" model="res.groups">
         <field name="name">Manage Lots / Serial Numbers</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_tracking_lot" model="res.groups">
         <field name="name">Manage Packages</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_adv_location" model="res.groups">
         <field name="name">Manage Push and Pull inventory flows</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_tracking_owner" model="res.groups">
         <field name="name">Manage Different Stock Owners</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 
     <record id="group_warning_stock" model="res.groups">
         <field name="name">A warning can be set on a partner (Stock)</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 </data>
 <data noupdate="1">
diff --git a/addons/uom/security/uom_security.xml b/addons/uom/security/uom_security.xml
index ebfe3e1178d..f7e0c0dd4d4 100644
--- a/addons/uom/security/uom_security.xml
+++ b/addons/uom/security/uom_security.xml
@@ -3,7 +3,6 @@
 <data noupdate="0">
     <record id="group_uom" model="res.groups">
         <field name="name">Manage Multiple Units of Measure</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 </data>
 </odoo>
diff --git a/addons/website_mass_mailing/security/mass_mailing_security.xml b/addons/website_mass_mailing/security/mass_mailing_security.xml
index 1f1438fcab3..95c9d4d56bb 100644
--- a/addons/website_mass_mailing/security/mass_mailing_security.xml
+++ b/addons/website_mass_mailing/security/mass_mailing_security.xml
@@ -2,6 +2,5 @@
 <odoo>
     <record id="group_website_popup_on_exit" model="res.groups">
         <field name="name">Use subscription pop up on the website</field>
-        <field name="category_id" ref="base.module_category_hidden"/>
     </record>
 </odoo>
diff --git a/addons/website_theme_install/models/ir_module_module.py b/addons/website_theme_install/models/ir_module_module.py
index 0ceea66f159..5350abea437 100644
--- a/addons/website_theme_install/models/ir_module_module.py
+++ b/addons/website_theme_install/models/ir_module_module.py
@@ -43,11 +43,10 @@ class IrModuleModule(models.Model):
     @api.multi
     def button_choose_theme(self):
         theme_category = self.env.ref('base.module_category_theme', False)
-        hidden_category = self.env.ref('base.module_category_hidden', False)
         theme_hidden_category = self.env.ref('base.module_category_theme_hidden', False)
 
         theme_category_id = theme_category.id if theme_category else 0
-        hidden_categories_ids = [hidden_category.id if hidden_category else 0, theme_hidden_category.id if theme_hidden_category else 0]
+        hidden_categories_ids = [theme_hidden_category.id if theme_hidden_category else 0]
 
         self.search([ # Uninstall the theme(s) which is (are) installed
             ('state', '=', 'installed'),
diff --git a/addons/website_theme_install/views/views.xml b/addons/website_theme_install/views/views.xml
index ed9b393ddf6..f080ee96005 100644
--- a/addons/website_theme_install/views/views.xml
+++ b/addons/website_theme_install/views/views.xml
@@ -67,7 +67,7 @@
         <field name="view_id" ref="theme_view_kanban"/>
         <field name="search_view_id" ref="theme_view_search"/>
         <field name="domain" eval="[
-            ('category_id', 'not in', [ref('base.module_category_hidden', False), ref('base.module_category_theme_hidden', False)]),
+            ('category_id', 'not in', [ref('base.module_category_theme_hidden', False)]),
             '|', ('category_id', '=', ref('base.module_category_theme', False)), ('category_id.parent_id', '=', ref('base.module_category_theme', False))
         ]"/>
     </record>
diff --git a/odoo/addons/base/data/ir_module_category_data.xml b/odoo/addons/base/data/ir_module_category_data.xml
index f31b210143f..aaf28c0bb86 100644
--- a/odoo/addons/base/data/ir_module_category_data.xml
+++ b/odoo/addons/base/data/ir_module_category_data.xml
@@ -1,12 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <odoo>
     <data>
-        <record model="ir.module.category" id="module_category_hidden">
-            <field name="name">Technical Settings</field>
-            <field name="sequence">0</field>
-            <field name="visible" eval="0" />
-        </record>
-
         <record model="ir.module.category" id="module_category_localization">
             <field name="name">Localization</field>
             <field name="visible" eval="0" />
@@ -166,11 +160,6 @@
             <field name="sequence">100</field>
         </record>
 
-        <record model="ir.module.category" id="module_category_usability">
-            <field name="name">Extra Rights</field>
-            <field name="sequence">101</field>
-        </record>
-
         <!-- add applications to base groups -->
         <record model="res.groups" id="group_erp_manager">
             <field name="category_id" ref="module_category_administration"/>
@@ -183,18 +172,6 @@
             <field name="category_id" ref="module_category_user_type"/>
         </record>
 
-        <record model="res.groups" id="group_multi_company">
-            <field name="category_id" ref="module_category_usability"/>
-        </record>
-
-        <record model="res.groups" id="group_multi_currency">
-            <field name="category_id" ref="module_category_usability"/>
-        </record>
-
-        <record model="res.groups" id="group_no_one">
-            <field name="category_id" ref="module_category_usability"/>
-        </record>
-
         <record id="group_portal" model="res.groups">
             <field name="category_id" ref="module_category_user_type"/>
         </record>
@@ -203,9 +180,5 @@
             <field name="category_id" ref="module_category_user_type"/>
         </record>
 
-        <record id="group_partner_manager" model="res.groups">
-            <field name="category_id" ref="module_category_usability"/>
-        </record>
-
     </data>
 </odoo>