1. Guarantee no more law suit against you what so every.
2. Set a move out date. Guarantee he will not return to your home or he will be trespassed. Guarantee that he will not damage your property before move out.
3. Anything left after that date will be consider as abandoned items. You can do whatever with those.
4. Dont give the check until he return the keys.
5. Change the locks
6. Find a witness when you sign the paper. Or notarized.
7. Photo the room after he moved out.
Anything else?