Annoying customer

Is there a way to tell someone I’m not interested ,I keep getting this sarcastic South African dude that keeps trying to engage conversation with me short of have history with this guy long time ago I carded his mom who’s about 50 for liquor she didn’t like it and he came into the store started cussing me out and ever since then he keeps coming in every so often thinking we’re friends my manger won’t do nothing