@river if u don't know him that well, maybe this would work.
"I appreciate your kind words, but I don't feel the same way. I have not interacted with you at all and I don't know what you are like as a person. On top of that I don't want to engage myself with a relationship until I'm in college. I'm sorry, I hope you understand.
"I appreciate your kind words, but I don't feel the same way. I have not interacted with you at all and I don't know what you are like as a person. On top of that I don't want to engage myself with a relationship until I'm in college. I'm sorry, I hope you understand.
I appreciate your courage though!"
This is literally word to word what I said to reject someone last time
This is literally word to word what I said to reject someone last time

Throwing rocks into a river as I await destiny