So I have the latest software iphone 4s not jailbroken.

So I deleted A person in my contact on my phone app but that person shows up on my messages app how do I deleted them?
Does not work in text messages for me? Like I want to send text message to him I search his name and it comes up. But he's deleted in my phone book so why is showing up my text message app when I want to go and send him A message A old number shows up.