Use Undo
to reverse the last action that has been applied to the picture on the screen, such as moving, deleting or mirroring an area, drawing a line, box or ellipse, or an effect that has been applied. Unlimited Undos are possible in the Draw window.
Only actions that change the picture can be reversed using Undo on the Draw window. For example, the Zoom commands cannot be reversed using Undo.
The Undo and Redo steps are reset when a new picture is opened.
Shortcuts
Quick Access Toolbar:
Keys: Ctrl + Z