Hi Lew-
Thanks for the great question, and thanks for using Total Upkeep to store your backups on Google Drive.
Navigate to Total Upkeep > Settings > Backup Storage and click on Update next to Google Drive. Then, click on the Delete Settings button, and close out of the pop-up menu.
Once you’ve deleted your settings, you’ll see the Authorize link reappear, where you’ll be able to change which Google Drive account you’re using.