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, open the Settings app , then tap Remove.
Tap Delete.
The music is removed from your Apple Watch and from all other devices that use the same Apple ID.
Note: You can also remove individual songs. If you swipe left on a song, tap PDF