Can I quickly delete all local music? I subscribe to iTunes Match. I recently did a massive song metadata (tag/ID3) update without using iTunes itself. This appears to have updated the metadata in iCloud, but another issue appeared.

In my Music list, for albums that changed more significantly, they are now listed twice. Once without a Cloud icon (the previously downloaded version), and one with a Cloud icon. There are many of these albums, and identifying them and manually deleting them has become cumbersome.

Is there a function within iOS to allow me to delete all locally downloaded music? Essentially resetting the Music library state?
Go to Settings; Tap on General > Usage > Music, then swipe across All Music and tap the delete button that appeared.

That should delete all your local music.