After seeing the crash command and how it always hangs your game which you need to use task manager to quit (At least I do)
This will simply close the game of the user you want effectively and wont leave it hanging!
/forcequit all - Quits everyone from the server immediately (Including you) useful for clearing up
/forcequit [ID] Forcequits the specified users id.
Update! Added a whitelist in server.lua along with 2 new commands!:
/forcesplit [all/id] Splits them into a weird singleplayer sort of session
/forceload [all/id] Sticks a user into an infinite loading screen