Well, I was in z same situation. But not actually I hated him but I was actually annoyed. Cuz I never by mistake I ever think more of him than our childhood friendship. But you know what he won't stop even if you tell him so or say you have bf; even if you say you love someone else. Thus the solution is time. The best mirror brings the best answer: one day he will choose to let you walk away. But it takes time till then just make sure you're not giving him wrong signs that makes him think you like him. And certainty don't be rude or mean towards him unless his actions gets to the point of him deserving the rudeness! Much love❤️,