How to remove Linked accounts with gmail account
You can view the accounts your Xfinity ID is linked to by navigating to Settings > Linked Accounts (under Account Details), or by clicking the account dropdown menu near the upper-right of any page on My Account.
To unlink from an account, select Edit, then Unlink next to the desired account. You can’t unlink from the account you’re currently viewing. After unlinking, you will no longer have access to Xfinity Services or My Account for that account. To regain access, the primary user for the account will need to add you as a user.