How do I get rid of my old boyfriends

Your old boyfriends huh?.
Tell them "Look, dude. Its just not working out. Its not me its you. I'm tired of your face. Let's break up. Don't call, don't write. Goodbye" and then walk away.
If that doesn't work, you can always try faking your death and moving to another country.

Yoi don't respond to them. They will get the message.

You can be straightforward with them, tell them that you don't want anything with them, or simply just ignore them, they will tire out eventually.