How do I get this guy off my back? He likes me A LOT. HELP!!!?

I do not feel there is an easy way to do this. The best thing you can do is make it very clear that you do not want to be with him. He's obviously very attached to you, and anything other than accepting him as a significant other is going to hurt his feelings. If you truly do not want to be with him, but want to preserve the friendship, you need to tell him you do not want to like him like that, but still want to be friends.