Honestly, if they can't learn not to abuse powers, remove them.
Money should not guarantee pardon.
But, it is an educational answer.
o ulx userdeny <player> <command> [<remove explicit allow or deny instead of outright denying: 0/1>] - Remove from a user's access.
o ulx userdenyid <SteamID, IP, or UniqueID> <command> [<remove explicit allow or deny instead of outright denying: 0/1>] - Remove from a user's access.
From server console, you can use
ulx userdeny Tom "ulx kick"
There's a way to do it in XGUI, but my apologies, I'm not taking the time to load it.
See also FAQ
https://forums.ulyssesmod.net/index.php/topic,3073.0.html