If you are referring to Firefox profiles: Go to "about:profiles" in a new tab -> Click on the "Remove" button associated with the profile you want to remove. '''Make sure you are removing the right profile. ''' Note: You are not able to remove the profile you are currently using. To fix this, launch a separate Firefox profile and close the instance of your previous Firefox profile. From the new profile, go to "about:profiles" again, and you should be able to remove any other profile.