How do I turn off a iPhone with a broken screen

Step #1: Press Power and Home buttons

If the touch screen is completely or partially inaccessible, you will just have press the Power and Home buttons simultaneously.

Step #2: Wait until it powers down

Keep the two buttons pressed down until your iPhone shuts down.

Step #3: Release the buttons

Now that the iPhone has shut itself down, release the Power and Home buttons to let it continue booting. This will restart the iPhone so it will be a good idea to:

• Back up your iPhone via iTunes.
• Bring it to an Apple Store for a fix if you’re under warranty.
• Bring it to a repair shop if you’re out of the one-year warranty.