How to friend zone for good

So I’ve sorta been texting this guy (nothing sexual or anything like that, just texting like I text all of my friends) who I’ve been with a couple of times before and I know he really likes me but I just want to be friends. I’ve told him this straight up but he thinks I’m just playing hard to get. It’s like if I have the slightest positive reaction to anything he texts me, he thinks I like him. I’m not sure what to do because he is always following me and trying to make out with me at parties. I don’t want to completely ignore him because he’s actually a nice person and a good friend. What should I do?