deauthorizing computers/devices

I'm trying to authorize my newer laptop but cannot because apparently there are 5 other computers authorized. When trying to deauthorize, the only thing that came up with my Audible acct which I deauthorized.

Then I tried to authorize my newer laptop but still getting notification that I cannot authorize more than 5 computers. I no longer have any of the other devices so obviously cannot do anyting with those.

HOW DO I DEAUTHORIZE when I no longer have