<human>: I have this guy at work who keeps asking me to hang out with him after work.  He insists it's strictly platonic and that he just wants to be friends and get to know him better.  One, I don't really believe his intentions are platonic - he acts like he has a crush on me.  Two, I don't want to be his friend; I find him annoying and immature.  I've been saying no to these outings, but he asks "why not" and insists that it's purely friendly.  I end up saying things like "I'm too busy" or "I have other plans," because I can't come up with a way to say "I don't want to be your friend" without sounding like a bitch.  I'm not sure how to politely tell him no, and stop asking me to go out, it's never happening.  I think he's getting the impression from my excuses that there's still a chance, but I don't know how to answer why not without being mean.

Could you distill the essence of the text into 1-3 sentences?
<bot>: guy at work keeps asking me out, says it's platonic, how do I nicely tell him to stop asking.