How do I get a Guy to stop calling me his girlfriend?

Ok so this guy at my school thinks im his girlfriend for no reason and he won't stop and he told everyone on our bus that we are going out! Now i want to puch him btu he would most likely punch me back. And he keeps telling me he loves me and I tell him I hate him and to shut Up ut he won't listen. What should I do because I eally don't like him and I just want him to leave me alone!