Garage Band is a hard drive hog

GarageBand sound libraries can use several gigabytes even when you rarely open the app. To review that storage on a current Mac, open Apple menu > System Settings > General > Storage. If Music Creation appears, open its Info button to review the installed content and the removal options macOS provides. Avoid manually deleting folders from the system Library. Before removing any sound content, check with other people who use the Mac and consider your other music apps. GarageBand, Logic Pro, and MainStage can share sound content, so removing it may affect their instruments and loops too. Keep a backup of your projects, and remove only content you know you no longer need. Required sounds may need to be downloaded again later.