Currently, users cannot deregister from Peppol.
There is an option to migrate away (i.e. request a migration key) but not every provider supports migration.
It is not straightforward to deregister from Peppol once a participant is marked as "prepared for migration",
so the users really should deregister instead.
Also, it is important to run the cron one last time for the user to fetch new documents/message status updates
they've received since the last time the cron ran.
closesodoo/odoo#128867
Signed-off-by: Laurent Smet (las) <las@odoo.com>