On a Mac, dragging an app to the Trash removes the app itself, but not the files it created while you used it: settings, caches, saved data, and sometimes background helpers that keep launching at login. Over time these leftovers add up. Here's how to remove an app completely.
1. Quit the app, then move it to the Trash
Quit the app first (⌘Q). Then open Finder › Applications, select the app, and choose File › Move to Trash (or press ⌘⌫). If macOS asks for your password, that's normal for apps installed for all users.
Some apps, such as security tools, drivers, and large creative suites, ship their own uninstaller. If an app has one, use it: it knows about system components that manual removal would miss.
2. Find the files it left behind
Most leftovers live in your user Library, named after the app or its bundle identifier (for example com.example.app). Tip: before deleting an app, you can get its bundle identifier in Terminal with osascript -e 'id of app "Example"'.
To look, choose Go › Go to Folder… in Finder and enter ~/Library, then check the folders above for items named after the app. Move only what clearly belongs to the app you removed; if you're unsure, leave it. Apps installed for all users can also have files in /Library/Application Support, /Library/LaunchAgents, and /Library/LaunchDaemons, which need an administrator password to change.
3. Turn off leftover login and background items
Open System Settings › General › Login Items & Extensions (called Login Items on older versions of macOS). Remove the app from Open at Login and switch off anything it left under Allow in the Background.
4. Command-line tools
Tools installed with Homebrew should be removed with Homebrew, so it can clean up links and dependencies: brew uninstall name for command-line tools, or brew uninstall --cask name for apps. Add --zap to a cask uninstall to also remove the app's support files where the cask defines them.
Uninstall apps completely with Binzide
Binzide's Apps workspace lists your apps and command-line tools. When you uninstall one, it finds the related support files, caches, and preferences, shows them before anything is removed, and moves them to the Trash so you can change your mind. Its System workspace also shows login items and background activity in one place.