There is currently no way to remove unfavourable ratings from Google, Yelp, TripAdvisor, or other major review services. This isn't to say that there's nothing you can do to stop them.
Make your response unique. Don't use the terms "customer" or "client" to refer to the person who left the review.
Thank you for your consideration.
Please accept my apologies and offer a solution.
Offer to deal with the issue on a one-on-one basis.
I'm sorry you had such a bad experience, but I sincerely appreciate you bringing this to my attention." "Thank you for drawing our notice to this. We're sorry you had such a poor time. "We'll work hard to improve."