Knowledgebase
How to disable the product review function in Magento
Magento has a built-in function that allows customers to write and post reviews of the products in your catalog. This function is enabled by default. If you want to turn off the review function, you can do that from the admin panel.
After you log in to the admin panel of your Magento go to System menu>Configuration, on the page that opens click on the Advanced button that's in the Advanced menu on the left, then, if it's not expanded, click on the Disable Modules Output panel on the right, set the Mage_Review drop-down menu to Disable and click on the Save Config button in the upper right corner. In this way customers will not be able to post reviews and rate products.