If you use Apple Music on your computer, you’ll find that the more you listen to music, the more your hard drive’s free space dwindles. Even if you don’t save music for offline listening, iTunes stores what you listen to in a cache. There’s a good reason for this: when you listen to something again, you don’t have to re-download it.
However, if you listen to a lot of different music, and don’t have a lot of disk space, then you may find that your free space is shrinking. It’s easy to clear this cache, but you can’t do it from within iTunes.
First quit iTunes. Then find it’s cache folder. On OS X, it’s ~/Library/Caches/com.apple.itunes, where ~ is a shortcut for your home folder. (If your user name is Alice, then the path would be /Users/alice/Library/Caches/com.apple.itunes.)
On Windows, Windows, it’s (replace USERNAME with you user name): C:\Users\USERNAME\AppData\Local\Apple Computer\iTunes\
When you’re there, you’1ll see the size of your cache. In this screenshot, you can see that mine is nearly 900 MB.
Select all these files and delete them, or delete the folder containing them. When you launch iTunes, it will recreate the necessary files; ones that tell iTunes which files are cached. As you play music, it will get stored here later. If you notice that your hard drive space is shrinking, come back and delete it again.
iTunes really should have two options related to this cache. The first should allow you to choose how large the maximum size of the cache is. And the second should be a button allowing you to delete the cache. For now, you don’t have those options, so you must do it manually.