You can delete music directly in the native Music app on iPhones running iOS 8. This procedure saves you the hassle of having to connect your iPhone to your computer every time you want to manage your library of songs. With the Music app you can delete songs, albums or an artist's whole catalog. To delete all the music from your iPhone, you need to use the Settings app.
Deleting Individual Songs in the Music App
To delete individual songs, tap the "Music" app icon on the iPhone's Home screen to launch the Music app. Select the album containing the song you want to delete to display its track list. Swipe your finger to the left across the name of the song you want to delete. When you make this gesture, a red Delete button appears next to the song. Tap the "Delete" button to remove the song from your iPhone.
Deleting Entire Albums and Artists in the Music App
You can delete a complete album or an artist's entire catalog from your iPhone using the Music app as well. To delete an album, tap the "Albums" icon at the bottom of the Music app to switch to Albums view, locate the album you want to delete, swipe it to the left and tap the "Delete" button. To delete all music by one particular artist, switch to Artists view and follow the same procedure. You can also delete playlists in this way.
Deleting All Music
You can delete all of the music from your iPhone in one fell swoop using the Settings app. Tap the "Settings" icon on the Home screen, touch "General" and then select "Usage." Tap "Manage Storage" and select "Music" to view information related to all music stored on your iPhone. Touch the "Edit" button in the top corner of your screen, tap the red "-" sign located next to the All Songs heading and then tap "Delete" to remove all music files from your device.
Deleting Music Using iTunes on Your Computer
If you'd rather use iTunes to delete music from your iPhone, connect the phone to your computer and launch iTunes if it doesn't open automatically. Select your iPhone on the list of connected devices, click the "Music" tab and deselect all the music you want to remove from the iPhone. Click "Sync" to remove the unchecked songs from the device.
Downloading Music Again
If you downloaded a song using iTunes or iTunes Match, an iCloud icon appears next to the song after you delete it. This icon indicates that you can download the song again at any time. Tap the iCloud icon to download the song. You can also connect your iPhone to your computer and sync deleted music back onto the iPhone using iTunes.