Force close an app
When you double-click the Home button, your recently used apps appear. The apps aren’t open, but they're in standby mode to help you navigate and multitask. You should force an app to close only when it’s unresponsive.
Follow the steps below to force close an app:
View your open apps
Double-click the Home button to show your most recently used apps. On an iPhone X, swipe up and pause.
Find the app to close
Swipe right or left to find the app that you want to close.
Swipe up to close
Swipe up on the app's preview to close the app. On an iPhone X, touch and hold the app, then swipe up to close it.