I remember this lol, to be fair no one knew how the guy managed todo it, because steam(the launcher) has checks for that, they assume the guy tried to run the steam command instead of clicking the launcher(don't do that)
/tmp is world-writable. If you get permission-errors, you should become suspicious.
Also, whenever you write "sudo rm -rf" you should quadruple-check if that's really what you want to do.
Non-interactively deleting entire directories in root space isn't something you should have to do normally.