Undo and Redo Last Operations
The Rich Editor allows you to undo and redo the last operation using special buttons (Undo and Redo) in the Common group in the Home tab.
The Undo command reverses the most recent action you have performed. To undo an action, click the Undo button in the Common group, or press CTRL+Z.
You can execute multiple Undo operations. To return the document to its previous state, just keep performing Undo.
The Redo command enables you to take back the last action you've undone. To redo an action, click the Redo button in the Common group, or press CTRL+Y.