How to delete all music on my iPhone

How do I delete all the music on my iPhone. I tried doing it through iTunes but it says my collection is not managed by iTunes and I don't want to erase and sync because all my apps are nicely backed up and sorted with iTunes.

I have only seen a way of deleting song by song on the phone.

Make sure you really want to delete all the music because they can’t be restored afterwards.

1. Open General » Usage in Settings.
2. Wait for iOS to load all the apps that take up the storage of your iPhone/iPad.
3. Find and select Music from the list.
4. You’ll see All Music in the list. Tap the Edit button on the top right, and choose to delete All Music.