For iPhone Users
- Press the Home button two times quickly. You'll see small previews of your recently used apps.
- Swipe left to find the app you want to close.
- Swipe up on the app's preview to close it.
For Android Users
Open the Notifications tab by dragging the top banner down and tap Settings. Scroll down till you see Apps and click on the button. In the list of running applications, select the application you wish to close and tap Force Stop.