well
cut your convos, start talking to him less, say you're busy, say you'll talk to him later, do talk to him later, but ignore him the next five times he messages you, then talk to him, then ignore again. this is a subtle way to keep them leeches away.
also, you could lie and say that you're just bicurious or just going through a phase. you could say that you're straight, too.
do you know how many times men have messaged me. a simple "im a lesbian" usually pushes them away
or like the others said, just say that you're uninterested
or you could say that you are now taken
messssssss