So I have few unwanted accounts that were supposed to be deleted when signing in an app with Google. How do I get rid of them?

They’re supposed to be removed from my Gmail app account list. But every time I use apps that require email accounts I always get this stupid list showing even some supposed to be removed accounts somehow appearing as well.
Is there not a way to get rid of them all the way through? Cause you would even just click on them and they’re already logging in instantly when choosing for account...
It’s annoying. They’re supposed to be both removed and logged off.
Some of these accounts are private and some people sometimes have me require for them to look thoroughly into my phone...