How stop background apps on an iPhone, iPad or iPod Touch running iOS
Many people have asked with the iPhone, iPad or iPod multi-tasking, is it possible to stop a background apps? With iOS 4, the iPhone, iPod and iPod Touch gained the ability to multi-task. Unfortunately while multi-tasking, the iOS devices keeps applications that you don't use in the background. These background apps are managed by the iOS device which keeps them in memory unless it runs out of ram. But these backgrounded apps can be a pain if you want extra memory for another app or if you want to stop an app that is running a service in the background like playing music. Fortunately, there is a way to stop any app running in the background on your iPhone/iPad/iPod touch.
Push the home twice quickly. This will bring up the multi-task bar which shows all of the apps running in the background on your device. If you select any application icon, it will be brought to the foreground.
Push and hold down you finger on one of the application icons. The applications will start to jump around similar to when you re-arrange applications on the home screen. Also a minus sign will appear on the upper left hand corner of the application icons.
If you push on one of the minus signs of an application, the app will be terminated and no longer run in the background. Terminate the applications that you want and push the home button to return your device to normal.