Removing recents from iMac Messages

There are tons of answers to this question, none of which work. I am on an iMac High Sierra. I click on Messages. I start to type in a name, an incorrect phone number comes up. It seems to have attached itself to a name in my address book. I look in address book under that persons name - the number IS NOT THERE. I do a search for that number - IT IS NOT THERE.

There is no little 'i' to click on to permanently remove this number. There is no menu to click delete. I go into my other apple products. This number does NOT come up when composing a message on the any other apple product. It is not in my address book on any of my other apple products.

I search everywhere and everything this number does not appear. The only time it appears is when I start to type in this person's name. I have deleted her from my address book, restarted the computer, turned off iCloud, restarted computer, searched again - it's nowhere to be found. Start a new message, there it is again. Now what?