Why can’t I delete an app on my Mac?
Either it is part of macOS, which Finder cannot delete, or it is still running. Quit it, including any menu bar helper, and try again; Apple suggests restarting or safe mode if it stays in use.
Read the guide: How to uninstall apps on Mac, and remove what they leave
How do I completely uninstall an app?
Run the maker’s uninstaller if there is one, otherwise move the app to the Trash, then remove its leftovers in Application Support, Containers and Caches and any login item it installed.
Read the guide: How to uninstall apps on Mac, and remove what they leave
How do I force uninstall an app on macOS?
There is no force option in Finder. Quit the app, remove its login items, restart if needed, then delete it normally. If the maker ships an uninstaller, that is the force option.
Read the guide: How to uninstall apps on Mac, and remove what they leave
Can I uninstall Apple’s built-in apps?
Apps installed with macOS such as Mail, Music, Books and Notes cannot be deleted with Finder. Apple apps from the App Store, such as Pages or Keynote, can be removed like any other app.
Read the guide: How to uninstall apps on Mac, and remove what they leave
What does an app leave behind after uninstalling?
Its settings, databases and downloaded content in Application Support, its sandbox data in Containers, its caches, preferences, and sometimes a login item or launch agent. None of it is removed by deleting the app.
Read the guide: Application Support folder on Mac: what is safe to delete
Can I delete the Application Support folder?
Not the folder itself, and not the subfolders of apps you still use. Subfolders named for apps you have already removed can go to the Trash; anything you cannot match to an app should stay.
Read the guide: Application Support folder on Mac: what is safe to delete
Can I delete the Containers or Group Containers folders?
Never the folders themselves or anything named com.apple. A container for an app you have removed is a leftover and can go; a group container shared by a suite you still use must stay.
Read the guide: Group Containers and Containers on Mac: safe to delete?
Why does a deleted app still seem to run?
A leftover helper is still launching at login. Open System Settings → General → Login Items & Extensions and remove anything that belonged to the app, then restart.
Read the guide: How to uninstall apps on Mac, and remove what they leave
Do I need an uninstaller app?
Not for most apps, but a free uninstaller automates the Library search for leftovers. The free-tools guide lists the ones their makers describe, with a note that we make ClearDisk and did not test them side by side.
Read the guide: Best free Mac cleaner: what macOS includes, then free apps