How do I make it clear to this guy that I don't want to date him?

There is this guy at my school that likes me. He is not my type and he has never spoken to me before but I hfound out from my friend that he was asking her for my number and asked her if I had a boyfriend. I thought that was kind of rude because my personal space kind of felt invaded because my phone number is something that should be private and not give out to without my consent. Anyways,I don't like him at all and I got upset with him and told him to not be going around asking people for my number. He thought it wasa normal thing to do and told me he wa just asking. I then told him it's not like I would give it to him anyway. The very next day, I felt him staring at me as I was doing my work on the computer. I then accidentally deleted one of my homework's and then he said in a flirty tone "Why did you do that?" I thought I already showed him that I'm not interested in him. I then gave him an attitude and said " It's not like it was on purpose." Then the next day, I went up to sign in my name. When I turned around, I saw him staring at me and smiling. I gave him a disgusted look and he immediately looked away. Then he starts trying to be nice to me and trying to find excuse to talk to me and I just want for him to leave me alone. Does he not know that I don't like him? I then felt a little sorry for being mean to him. So I decided to be nice and talk to him. He asked for my number again and I decided to be nice and give it to him. Bad idea because he was all over me again and took it the wrong way and is still flirty with me. He sends me the same text message like three or four times whenever I don't reply right away. He then asks me if I have a boyfriend. I told him I only see him as a friend. That he's a nice person but I don't like him as anything more than a friend. He then didn't accept my feelings abut him and told him that "We can fall in love naturally and that he would treat me like a queen." I told him that I'm sorry but I only see him as a friend. That I don't like him that way. He still kept on bothering me leaving me voicemails saying, "Hey baby it's me, Please call me back. I want to talk to you." Why does he call me baby if we are not even dating! I went out to lunch with him only one time just to be polite of his invitation but I decided to bring a friend along so that it wouldn't be considered as a date. After that, he started telling everyone that I'm going out with him which is not even true. I then confronted to him about it and he told me he never said that. Ofcourse he said that because everyone is questioning me if I'm going out with him which I'm not. He then wanted me to go to a party with him after I already told him I was at another party. How can I just get him to leave me alone. I tried everything I could.