How To Off iPhone X
On the iPhone X, the old way of turning off your iPhone has gone the way of the headphone jack. No longer do you press and hold the Side/power button to power down; that action is now reserved for summoning Siri.
Here’s what you do instead when you want to turn off the iPhone X.
1. Press and hold the side button and either volume button. Make sure you press down long enough; pressing too short could result in a screen shot if you’re using the Volume Up Button.
2. Swipe the power icon from the left to the right on your screen to turn off your iPhone X.