How do I get rid of a guy?

I have this guy in my homeroom that is obsessed with me. He always tells me I'm beautiful and has asked me to marry him before. I'm only in college and i'm not planning to spend the rest of my life with this guy. He's never asked me out before, and i'm not sure if i would go out with him. All my friends say i should go out with him, but i'm not sure. What do i do?