If you are a fairly heavy user of your Mac, you end up trying out Apps for different purposes. This trial and error process means you need to Delete Apps occasionally. That involves Deleting App Store Apps and probably third party Apps as well. There are different ways to Delete Apps on the Mac, this article covers every way possible. It also talks about using an App like Hazel to cleanup after an App is Deleted. Apps install stuff all over your hard drive. If you just Delete the App itself, all of the other stuff the App installed remains, hence using a cleanup App is a good idea. CleanMyMac also has a feature that removes all of the Deleted Apps files.