Can anonymous friends send text messages?

No, first of all, posting anonymously will expose all your friends and let you choose who to be anonymous with. You can't post with him without him. Like you said, you deleted him, and he is not in your friends list. If you are in him, you can. I added a friend before, and you deleted him, but he didn't delete you. I can send you a message. Blackout him next time you send a message!