Is there a proper way to reject a crush? How do you reject a crush?

I've crushed so many hearts and the last two people that had a crush on me were too understanding that it feels wrong. Every time, I feel bad for rejecting them even if I don't see them in that way. Even with so many heartbreaks, I'm still inexperienced in rejecting them. So, is there a proper way to reject a crush? How do you reject a crush?