Fixing mistakes on your iPhone is very easy. While the Mac has Command-Z, iPhone itself has its own feature that rectifies mistakes: Shake to Undo. With Shake to Undo turned on, iOS users can quickly fix mistakes. Shaking your device to go back or undo a mistake has been around since 2009 and iOS 3 (called iPhone OS back then). And it’s definitely one of the most overlooked features on iOS.
Rather than a system button or symbol to undo, all one has to do is shake his/her iPhone. For most iPhone users it’s a forgotten feature, but writer John Gruber recently gave it newfound attention with thoughtful analysis and the revelation that it was actually originally considered a joke.
Shake to undo feature is turned on by default and can be turned off by Settings>General>Asessibility. But keep one thing in mind, there is no other undo function for iOS