Found this one a few weeks back.

 

We have users in the Agent Role and Management Role. Since we do not want Agents or Managers to delete Tickets, we set Ticket Permissions to "Custom" and we unchecked "Mark as Deleted". This to me means they cannot mark tickets as deleted.

 

Sounds great in theory but it doesn't work. Those roles no longer have a "Delete" button when viewing the Tickets but they can still simply chose "Delete" from the Ticket Context Menu (Right-Click on a ticket, click delete)