What reason do you have for removing this profile like you had a problem with it and created a new profile ? It looks that the profile is (still) locked for some reason. *https://searchfox.org/mozilla-release/source/toolkit/content/aboutProfiles.js#66 You can remove this profile manually from the hard drive if you can't unlock this profile and afterward cleanup profiles.ini via about:profiles. *https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding Firefox uses two locations for the Firefox profile folder. Primary location used for the main profile that keeps your personal data (Root Directory on about:profiles). *~/Library/Application Support/Firefox/Profiles/<profile> Secondary location used for the disk cache and other temporary files (Local Directory on about:profiles). *~/Library/Caches/Firefox/Profiles/<profile>