Reviews that are connected through a direct integration can respond straight within the application and can also delete previously sent responses, just the same.
How to delete a response:
Go to the Sent box in Reviews Inbox,
Select the review whose response you wish to delete,
Use the trashcan icon to delete your response.
Responses typically take between 1-2 minutes to remove from Google. Their removal can be confirmed by going to the GMB page and finding the review in question.