As things stand,you can't be friends-so man up(pardon the pun) and tell him to stop it with the texting etc.

Then go no contact-as in no replying to texts-delete them without reading them-no phonecalls etc.

I have told him I only want us to be friends and that I do not love him anymore. But he seem deluded. He said he thinks I still like him in a way and that he's just gonna keep trying to get me back. I have told him in every way possible. I really wanna stay friends with him because I think he would a better friend than bf. How do I tell him to back off without hurting his feelings? and staying just friends with him?

I advise you to make a clean break for right now -- no answering his texts or talking to him by phone or in person. This doesn't mean you will never talk with him in the future or be his friend, but, for his sake, since he can't seem to get past his infatuation with you, you are going to have to be the stronger and smarter one. Don't tell him this, because he won't agree, but he needs time to heal and get on with his life before you two can ever be friends.

Make a clean break for now. You can do it.

When you make the decision to break up with someone you do NOT try to keep them in your life as a friend, because you both need time to let the emotional dust settle, and have a proper healing.

Make this a clean break, and leave each other alone for a while, so you both can breath and accept this relationship is over, and not have false hope that two incompatible types of people should try again.

If you become friends later, then fine, but it sure won't happen now, but trying to stay friends will make it worse, for you both.