The first step of uninstalling apps on Mac completely without leftover files is to quit the app. Go to Finder > Applications, drag the app to Trash, but don't empty it yet. Now, press Command + Shift + G in Finder and locate the following folders: ~/Library/Application Support, ~/Library/Preferences, and ~/Library/Caches. Look for files related to the app name and move them to Trash. After deleting the leftover files, emptying the Trash will erase everything. This manual way is good for getting rid of the leftover data, settings, and cache files that were there after the app itself was removed.