WP Rich Snippets Anonymous User Reviews Addon will allow you to accept anonymous user reviews on your website, it will make the name and email field completely optional so that Reviewers can submit a review without having to provide their Name or Email address and stay anonymous.
Add-on Settings Page
The settings page have a few options for customizing how the add-on works.
If at some point you needed to totally remove the Name and Email fields, no problem! The Anonymous add-on will allow you to hide Name and Email fields completely from the form, this easily can be done within the add-on settings page.