is the switch over as easy as installing SuperSU? I think I tried that once (flashing superSU from a zip in recovery) and all my root access ended up broken. Had to Nandroid back via recovery.
The easiest was is just update thru the play store to supersu. Simply install supersu, update your su binaries thru supersu (might do the on its own but verify it) then you can uninstall superuser.
Quick thing: I went to remove Superuser, and can't seem to find it in the TiBu list. Does it have a strange name? Or is it hidden for some reason? Just trying to get a single SU program. LOL
Just use native manage app or play store to uninstall
Whoops! Forgot it was a system app lol. I couldn't find it in TB either. Use a file manager to remove from system and reboot. Might need to wipe caches and fix permissions from recovery. If you don't want to keep superuser you might want to go with the flash able version as it will remove it in the process