how do I turn off the music app (fm radio)
how do I turn off the music app on my iphone (fm radio)?
iPhone 5c, iOS 8.3
It's not entirely clear what you mean. To stop the music in the built in Music app, tap the pause button (two vertical lines). As there are no moving parts to the Music app, there is no need for a stop button.
The phone has no FM receiving abilities. If you're talking about an app called "FM Radio", you probably stop the music on that by pressing the pause button but, best to contact the developer for more information.