When you double-tap the home button of your iPad or iPhone, the dock
will show a list of all the recently used apps and some of them could
still be running in the background.
You tap and hold your finger
on the app icon until it begins to jiggle and you can then press the red
“minus” sign to close one or more of these background apps. If a
particular app is not running, this action will simply remove its
listing from the multitasking bar.
If you receive a delete confirmation screen, you need to cancel and re-read the instructions above.