I'm going out with this guy i don't like now i don't know what to do...?

This guys asked me to go to the movies with him and i said i would because i didn't want to turn him down and hurt his feelings. However, halfway through the movie he asked me if i would go out with him and i panicked and said yes. I know it was the wrong thing to do and everything, and i shouldn't have said yes. I only like him as a friend, but now that i've said yes i don't want to immediately break it off with him and hurt his feelings because i still want to remain friends with him. What should i do? Should i end it with him, and if so how long should i wait to do it and how should i do it? Please help, i really don't want to lead him on, but i don't want to embarr him either because he already told all his friends he was going out wih me....