How to turn off a Iphone thats far away?

My nephew accidently left her iphone at school. It has her alarms on at 6:15 Am and 7:35 Am. I don't know how to turn it off or what to do! I don't want my nephew to get in trouble. The alarms are really loud i'm afraind he will be yelled at school by the princepal. Please i need a answer until 4-19. How do i turn a iphone off or silent when its far away?

Download the app Find My iphone, then have him sign in on his apple id then control it from there. That should help

Bomb the school then, there shouldn't be a prob.