There is no tried and true way to make emotions disappear, sadly. But you can try and wean yourself off or let them fade by distracting yourself. Talk to other people, take up a hobby, anything to get your mind off the person who is not right for you.
Of course, usually when someone comes to be with such strong feelings they are just scared. So I would suggest trying to talk to him about his behavior first. Don't run from how you feel!