Thank you @will for your help!
I will post your solution here, in case someone googles to this post in the future. I did it the hard way and it worked.
If (user) has access to their computer, please ask them to open Rhino and run the _Logout command. It may be necessary to do this in both Rhino 6 and Rhino 7, (if) both are currently in use on this computer.
If you don’t have access to the computer, you can do the following…