Google finally ripped the bandage off and officially shut down Google Play Music. Although, when opening the app it still says that Google Play Music will soon shut down so you have to make the migration to YouTube Music. In other regions, it doesn’t give you any other options except transferring your data to YouTube Music.
There’s also the “Manage your data” button that takes you to the GPM website and lets you download your full library and delete it later. You can also delete your recommendation history.
However, if you have any songs downloaded onto your device, you’d have to either delete the Google Play Music app or at least clear the user data and cache in the App info sub-menu.