Is it possible to completely turn off Google Reviews for a business?
It's not possible for Local Businesses to turn off the review feature in Google My Business listings. I mean, there is no method to disable reviews like Facebook has. Negative reviews are a very natural thing and are going to happen to even the best businesses in the world. It's not a bad thing at all as long as you are getting positive reviews as well.
Anyways, if you come across an inappropriate review on your Google My Business listings that violates the review guidelines you can Flag Inappropriate Reviews and Google will review it.