If possible and if you feel safe to do so, please tell him you are not interested. If that isn't an option or he persists you can ghost him (or block him) or weird him out by saying outrageous shit like absurd goals for a relationship (must only text me, only look at me, must cut off all contact with friends,etc,etc) or just some weird stuff you feel would drive him away. It will be awkward either way if hes hitting on you and you dont want that.
And im including this just incase it might make you feel better because its kinda funny, today I sent a video of my friend doing low squats going "Thank you thank you thank you" to another friend instead of a groupchat, he has never met this other friend before. Aswell as her dancing to yodelling. (She was okay with it)

So...I sent a file I was supposed to sent to this group but I accidentally sent it to another group. The girlies immediately texted me and this one guys also texted me about it...and he now is hitting on me. He is about to make me suicidal. Should I just ghost him but we in the same class and we take the same major so all our class are the same:D. This gonna be awkward.