How to delete recent contact auto fill when writing a new text message?

I try to compose a new message. Once I type, say, 4, I get all the names and numbers that has the number 4 in the contact name or phone number that it seems I have text message before pops up with the option of selecting one as a quick auto-fill. When the number is NOT part of my contact I do the number with a ! sign and an option to clear it from recent history. But when the number is in my contact list I do not get the option of clearing it from the the recent history. I am trying to clear all of this history so that if I am composing a new message, there is no indication that I had ever had a text message conversation with these users.

Hope this helps, let me know if more info is required.