If you have a storefront URL that is already claimed to an existing Google Merchant Center (GMC) account, you can unclaim a claimed URL through Google.
When creating a GMC account in Google Shopping ads Channel, Magento attempts to automatically claim your store URL(s) after submission, but already-claimed sites will fail this automated process. Already-claimed sites must be unclaimed from one GMC account before claiming to another GMC account, as Google allows only one website URL to be associated with one GMC account.
Once unclaimed, a site may be manually verified and claimed.
To unclaim a claimed URL:
Login and open your GMC account in Google.
Select Business Information, then click About your business.
Expand the claimed Magento website and delete it.
Click Save to update removals from your account.
Unclaimed and Clear GMC Account
Review the listed URLs on your account to ensure the claims are removed.