Depending on the source, you have two ways to deal with unwanted music in the Play Music app's library on your Samsung Galaxy tablet. The method you use depends on whether or not the song is stored directly on the tablet:
For music stored on the device, simply locate the song or album and touch the Menu icon. Choose the Delete command. Touch the OK button to remove the song. And voila! The song is no longer on your tablet!
If you don't see a Delete command on the menu, the song is available only through Google Play Music. To remove the song, log into Google Play. View your library to locate the song. Click the Menu icon by a song and then choose the Delete command. Click the Delete Song button to confirm.
Now that you've cleaned up your music library, it's time to add some new tunes!