He can move out.

tell him to start paying rent and helping out or eviction proceedings will begin. sadly you can't just have the locks changed while he's gone or I'd tell you to do that.

He's not paying rent because you let him.

listen you all do, what you want to do. but I will never charge my child rent for living in my house. they will get chores, like cooking a night a week, and they will do their own laundry. but rent? never. I will help them invest their "rent" money in either stock, bonds or pension depending on need. but I won't take from my child. in my opinion being a parent is much like being an officer in the army. you are responsible for the well being of your subordinates. never put yourself in a position where you take from them.

23 isn't too old to discipline. I recommend violence.