The above process nukes the GarageBand app and takes care of its large files, but there are still some small preference and support files that may be left behind.
Finally, reboot to ensure that everything related to GarageBand is gone. With all files and folders moved to the Trash, right-click on the Trash icon in your Dock and choose Empty Trash. Then just paste the folder’s location into the box and press Go. If you need a quick way to get to the folders in your System Library folder, open Finder and press Command-Shift-G to launch the Go to Folder window. Once you’re all backed up, head to the locations listed above and delete them one by one, authenticating with an administrator account if asked. This can be accomplished via something like Time Machine or with the creation of a bootable clone with an app like Carbon Copy Cloner.
To delete GarageBand, first quit all open applications and make a full system backup to be on the safe side. It may not seem like much, especially as storage capacities continue to rise, but 3GB can make a huge difference for those with small SSDs. Under normal circumstances, however, users looking to delete GarageBand can expect to save around 3GB of space. You should not delete this folder (or the Logic folder) if you are using Logic Pro. *Note that the size of the Apple Loops directory will vary depending on the number and type of loops downloaded by the user. Macintosh HD/Library/Audio/Apple Loops (up to 10GB) *.Macintosh HD/Library/Application Support/Logic (880MB).Macintosh HD/Library/Application Support/GarageBand (995MB).Macintosh HD/Applications/GarageBand.app (1.16GB).