This article explains how to close an app on iPhone. Instructions apply to all devices running iOS 6 or later.
How to Close All Open Apps on iPhone 11
The process for closing apps on the iPhone X and newer models like the iPhone XR and iPhone 11 is a little different than previous iPhones. That's because these models don't have a Home button, so the way you bring up the multitasking screen is a bit different. Here's how to do it:
Swipe up from the bottom of the screen and pause about halfway down the screen to open the multitasking view.
Swipe the app you want to close from the top of the screen.
