iOS 7 comes with a completely revamped app switcher. So if you’re wondering how to close an app then you’ve come to the right place.
When you double-click the Home button to access the multitasking tray/app switcher, you will be greeted with apps running in the background displayed in an all-new card-based interface. You can swipe left or right to see more. You can switch to another app, by tapping it.
How to close an app?
To kill an app running in the background or force it to quit, double-click on the Home button to access the new app switcher or multitasking tray and then swipe up on the app that you want to close. You can close multiple apps (up to 3 apps) at a time using multiple fingers.
Check out this video to see how it is done:
If you’ve any questions, please feel free to leave them in the comments.