To give users the possibility to report a review they do not consider appropriate, go to Voting/Review settings > Review settings. Through the option Inappropriate reviews, you can decide whether only registered or all users can report appropriate content.
To report a review as inappropriate, the user must click on the dedicated button in the review box.
The reported review will be marked as inappropriate within the “Reviews” section through the specific symbol followed by the number of abuse reports collected so far. All inappropriate reviews are automatically shown if you click on the filter “Inappropriate content”.
You can also automatically hide the review in case it has collected a specific number of reports that you must have previously set in “Hiding threshold”. By setting “0” as a value, no threshold will be set, so you will receive abuse reports, but the review will never be hidden automatically.
A review that collects the maximum number of reports set will be automatically unapproved. To enable it once again, you have to approve it manually.