Remove the old texts from your phone, the messages that gave you hope, that made you believe that the two of you could be something. Delete them all. Don't give yourself the opportunity to search for meaning. Maybe at one time these messages would signify a future, but now they are simply the past. Let them be so. Delete those texts. 
And then erase the tough texts, too, the ones where he took too long to reply, the ones where he told you he wasn't looking for anything serious. Get rid of the texts that confirmed your worst fears: he was not invested in you and never would be. You got the information you needed. No need to keep opening the wounds. Erase the texts. It's okay.
And now scroll to his name one last time. And almost send him a message. Draft out a declaration saying you still want to be friends, even though you both know that's not true. Lace together these beautiful lies stitched with hope and good intentions, and hover your thumb above "Send". But instead, backspace it all. 
And then delete his number.
Stare at your phone for a minute to let it sink in that you won't be reaching out to him on your toughest nights and that he won't be the one to comfort you. You won't get to hear how his mom is doing, you won't get to see him on New Years Eve. Let it all sink in that his name is no longer going to pop up on your screen when he gets home from school.
He is no longer a part of your life and you are no longer a part of his. And this is okay. You are okay. 
Now put your phone down. Walk away from it all for a while. Feel the distinct mixture of sadness and freedom pumping through your veins, the feeling that only comes with the end of something painful and the begining of something more. Be proud- you deleted his number, which is one step closer to removing him from your heart.