As far as I know, your Google account is its own email. Sounds like you got stuck in “account hell”.
I assume that means Windows, right?
You need to open each Plex client device/app you have and log it out of the old account.
Now shut down the Windows Plex server using its task tray icon.
Then perform the procedure as described in here: You need to reclaim your server, but don't dare to touch the Windows Registry
to remove the server from the old account.
Once you’ve reclaimed the server into the new account,
open each Plex client device/app and sign them into the new account as well.
