If you’re running out of room to store music on your Apple Watch, you may want to remove the music that was automatically added to your watch or music that you no longer listen to.
Note: To see how much music is stored on your Apple Watch, go to the Settings app , tap Library, then tap Playlists or Albums.
Tap a playlist or album, tap , tap Delete from Library, then tap Delete. The song is removed from your Apple Watch, from any playlists it’s in, and from all other devices that use the same Apple Account.