Swipe up from the bottom of the screen and pause in the middle to open the App Switcher
Swipe left or right to find the app you want to close
Swipe the app’s preview up and off the top of the screen
Repeat for any other apps you want to close
If the app doesn’t close, try swiping up more firmly and completely off the screen
To return to the Home screen, tap the Home button or swipe up from the bottom (depending on your iPad model)