Having first-hand experience with our forum software, I can say that making a "Retired Staff" group will take no more than 2 minutes. The permission system is literally a checkbox system.
(not from out forum). For making the "Retired Staff" group, all you need to do is copy the default member group's permissions since all that is being asked if for a simple prefix. a 5-year-old can do it....
Now, just like on the old forum, only [Staff], now [Admin], would be able to achieve this rank. No [Staff]/[Admin] has ever been demoted, they all resigned.