Let him have his own misconceptions. You aren't actually obligated to clear anything up and if you fluster some more, it'll definitely prove his point of you liking him. Want him to not get the wrong idea? Leave him be. Eventually, he'll pick it up. If not, he's got a bloated ego ┑( ̄Д  ̄)┍
I'm a guy so this might be bad advice lol but I wouldn't really find it weird if some one were to just tell me that they not like me if they thought I thought I liked them. Plus if he likes u then that would be good info for him and if he don't like u then no awkward friendship :D.
But if u don't like that idea then I guess you could slip something in casually during a conversation where it's relevant along the lines of your not my type xD, but if they have an ego then probably rip friendship.
Ik how u feel I wouldn't be able to do the first one to cos I'm awkward aswell :P
Soooo... There is this dude he likes teasing me. Like, 'flirt' with me (and other girls) but in a joking way. Yaaas in a JOKING
WAY. It is fucking obvious that he is not serious about me. But then this stupid me got all conscious around him and now i have a feeling that he thinks that i like him (WELL I DON'T). WAAAH HELP. I WANT HIMTO STOP THINKING DAT I LIKE HIM BECAUSE I DON'T. REALLY. (● ̄(エ) ̄●)