How would you go about this?

Soo I took out something for my ex under my credit. It’s using my social security but the item itself is under his name. Well, turns out he was cheating on me and he’s not even making the payments on it. I’m LIVID so I want to take it away from him. But since it’s under his name, would that change anything? I’m thinking of just reselling it or something. I just don’t want his lyingass to have it.