Use the Undo tool to reverse the last editing action.
This tool will reverse the last action, however, not all actions can be undone. If the button is disabled , Undo is not available. The action can only be undone on the Layer you created it. For example, you cannot undo an action that you made on Layer 2 if you are currently on Layer 1 of the Quilt worktable. Adding to Sketchbook will clear the undo list.
Tip: Before using Undo, you can read a description of the action that will be undone by clicking Edit on the main menu and reading the text next to the Undo command.
PC keyboard shortcut: CTRL+Z
Mac keyboard shortcut: CMD + Z