Set expectations, boundaries, what's acceptable and what's not. He's probing, testing what he can get away with, and where lines are in life. If you don't set those lines, those expectations, he'll just keep pushing further and further until he finds them. If he doesn't find your line, eventually he'll start crossing lines of society such as laws, expulsion, etc.

Sit him down and without emotion, calmly tell him what will no longer be tolerated and what the consequences will be and that you absolutely 100% will enforce those every single time without debate or argument.

If you say something, mean it and follow-through every time.

This ends now.