The visibility of a particular review is in your control.
You can make Publish or Un-Publish reviews depending on the type of reviews that you would like your customers to see.
From the Reviews section under Scale, you can locate a particular review in question.
Next to the review, there is a "Publish" or "Un-publish" button that is available.
Clicking on Publish will make the review visible and Un-publish will remove it from the activity page.