I need some helpful thoughts

So I recently was divorced, my ex wife left me with her dog and brother. The dog is cool but the brother is a disaster.

So I need help with what to do. I clean the whole apparent and he destroys it. He leaves dishes I'm the sink with food, he leaves plants and dirt on counter tops for days. He acts like a child that can't be disciplined because he knows I can't touch him. He is 25 years old. One day I walked into his room to find plates and cups that disappeared. And I see what's In the photos. So what should I do? I'm stuck with him on the lease for a year . Please please comment with some advice or tips. By the way he pays maybe 25% of all the bills to live here with me picking up 75%.