To temporarily disable Related Products Manager:
Click on System->Configuration->Advanced and set CommerceStack_Recommender to disabled then clear your cache.
To permanently remove Related Products Manager:
Use Magento Connect Manager to uninstall (recommended), or:
- Delete the following files and directories:
- (for versions prior to 3.0) js/commercestack/adminhtml/recommender.js
- Drop the database table recommender_product_link
- Run the following query in the database: DELETE FROM core_resource WHERE code=’recommender_setup’;