Here are the steps to exit Zello in iPhone 4 and later:
- Press the iPhone home button to exit Zello. (The physical button on the bottom of your iPhone with a white square.)
- Press the iPhone home button twice and a screens pop up.
- Find the Zello icon and Zello screen.
- Press and drag the Zello screen up.
Press the iPhone button once to go back to the home screen.