Have you read our FAQ? I do not think so. If does not work after disabling problem is in your WordPress and your lodging. All others can work.
Or change the rating to 5 stars or is not supported.
https://wordpress.org/plugins/remove-category-url/faq/
Had the same issue as Mohsen, Valerio.
After guessing at and trying a number of solutions, I tried activating another theme (which returned the pages correctly) and then re-activated the actual theme I was using (which returned 404 errors again).
So I deleted the actual theme I was using and reinstalled it. It turned out okay. Hope this helps with any future similar situations.
LymanX, Mohsen.
Do not just disable the plugin, and disable you should look your .htaccess. Some providers do not allow change by the plugin. After looking, and remove unnecessary you should save permanent links again.
