About App Store (including ITunes, Google, and Apple) Reviews
App stores do not remove or filter inappropriate reviews about any app, and there is no way for Blackboard or your district/school administrators to delete or filter app reviews. However, you can submit a request to Support/App Team and they can forward it to Apple or Google for removal.
The store reserves the right to remove the review or not after reviewing the developer request. Additionally, Google allows developers to respond to a review if there is a question or incorrect information posted. Apple on the other hand does not allow response at all.