When you delete apps on macOS by dragging them to the Trash, temporary files, caches, preferences, and resources can get left behind.
How AppTrash Helps
AppTrash makes cleaning up unwanted files after removing Mac apps easy. When you drag an app to the trash, it finds related files and offers to remove them as well. You can selectively pick which files to remove, or go with all of them.
Requires macOS 10.13 "High Sierra"