LoL friendzone him. "your like a brother to me" "your my best FRIEND" theres many ways to tell him to **** off >.>
Or just tell him your gay. he wont even bother with you.
may be a bit harsh how i say it but thats litterally what happens in real life. all the time. wether you want to notice it or not.
Immediately change the subject, and keep going.
tell them your considering changing gender :)
You tell him "I'm truly flattered that you feel this way towards me, but I'm not diggin you like that. You're a cool guy, but I'm not interested."
just explain why not with more details
Just say "Sorry, I'm not interested in you"