Dragging an app from Applications to the Trash removes the app itself. Its settings, caches, downloaded data and background helpers stay in your Library folder. For most apps that’s a few megabytes; for chat apps, editors, games and anything with an offline library, it can be gigabytes.
Uninstalling completely is three steps: find the app’s ID, remove the app, then remove what it left.
Before you start: use the app’s own uninstaller if it has one
Apps that install drivers, system extensions or services, such as antivirus software, VPNs, Docker, Adobe Creative Cloud and audio tools, usually come with an uninstaller. Look in the app’s folder, its menus, or the disk image it came on. It removes parts you can’t find by hand.
1. Find the app’s ID
Most leftovers are named after the app’s bundle identifier, such as com.tinyspeck.slackmacgap for Slack, rather than its name. While the app is still installed, get it in Terminal:
osascript -e 'id of app "Slack"'2. Remove the app
Quit it first. Then drag it from Applications to the Trash. If it was installed from the App Store, macOS may ask for your password.
3. Remove what it left behind
In Finder, choose Go › Go to Folder and open each of these. Look for a folder or file named after the app or its ID:
~/Library/Application Support: the app’s data. Often the largest.~/Library/Caches: caches, safe to remove.~/Library/Containers: all the data of App Store and sandboxed apps.~/Library/Preferences: settings files ending in.plist.~/Library/Saved Application State: the windows it had open.~/Library/HTTPStoragesand~/Library/Logs: web data and logs.~/Library/LaunchAgents: helpers that start at login. See Background Items Added.
Move what you find to the Trash, restart, check that nothing you still use has changed, then empty the Trash.
Be careful with shared folders
~/Library/Group Containers holds data shared between apps from the same developer. A folder there can belong to several apps at once: Microsoft’s Office apps share one, for example. Only remove a group container when you’ve removed every app from that developer.
The same goes for anything that mentions the developer rather than the app you’re removing.
Reinstalling later
If you think you might come back to the app, remove the app and its caches but keep its folder in Application Support. When you reinstall it, your settings and data are still there.
Which apps are worth removing?
In System Settings › General › Storage, click ⓘ next to Applications to see apps by size and when you last opened them. Apps you haven’t opened in months are the easiest space to win back. See how to free up space safely.
Unslow’s uninstaller finds an app’s leftovers in your Library folder by its ID, lists every file with its size before anything moves, never ticks shared folders for you, and moves everything to the Trash so you can put it back.