You can undo any changes you made quite easily. On your controller push your thumbstick to the left towards undo, and it will revert back to the previous change. You can continue clicking the undo option to go back to further changes, but only as far back as your current session and there is a limit to the amount of undo steps available. After using the undo option, you can redo by pushing your thumbstick right.

Seen above are the undo and redo buttons.