How to reject? help, mystery guy, i know him but i dont know which guy is the guy that like me.?

ok, so i've only had 2 boyfriends my entire life and my cuz has been telling me someone likes me and they wanna ask me out, and im still wondering who my mystery guy is, i dont have a clue, but he still never revealed himself, althought my cuzen has been talking to him and my cuzen told me i got him hypnotized and he keeps calling him to ask questions about me, so im wondering, if i dont like this guy, how can i reject him without hurting him in anyway, becuz when i asked my cuzen y he wont reveal himself any soonner and he said cuz he's scared if i reject him. so im stuck between a rock and a hard spot, i rlly also wanna know the right way to break up with somone and the right way to reject someone