Delete account for apple music on an apple iphone6

You can do it through the music app in the

For You Tab - your profile - Manage Subscription

or

View, change, or cancel your subscriptions - Apple Support

you can do this on your phone in settings or as instructed in the above link 

Go to Settings > [your name] > iTunes & App Store.

Tap your Apple ID at the top of the screen, then tap View Apple ID. You might need to sign in with your Apple ID.

Scroll to Subscriptions, then tap it.

Tap the subscription that you want to manage. ...

Use the options to manage your subscription.