Prevent agents from marking tickets as unassigned

[MrWizard77]

Is there a way to prevent agents from changing tickets back to unassigned?  Currently tickets are auto-assigned to improve SLA.  However, agents can move ticket back to unassigned.  The ticket then sits unassigned.

[ErikT]

@MrWizard77 
Unfortunately, other than deleting the unassigned state, there is no way to prevent agents from changing the ticket state to unassigned.