This wikiHow teaches you how to close apps that you left from the main page, but no longer use on your iPhone, iPad, or iPod Touch.
Step
Step 1. Unlock your device
To unlock it, press the Sleep/Wake button in the top-right corner of the device, then enter the passcode or tap the Home button to enter Touch ID if necessary.
To manage open applications, the device must be active and unlocked (eg not displaying a lock window or passcode)
Step 2. Press the Home button twice
The button is circular and is below the screen on the front of the phone. All open applications will be displayed behind the Home screen.
Step 3. Touch and drag the app you want to close to the top side of the screen
When the application disappears, the application has been successfully closed.