Use the Undo button to reverse the last command.

Click the Undo button to reverse the last operation. 

Any command or operation that changes the design can be reversed (e.g. moving the borders, resizing or deleting an object, etc.).

Delete Object

Click on the desired object and click the Delete button. 

The object is deleted. 

Undo Last Command

Click the Undo button to reverse the last command performed, which in this case was deleting an object.  

The deleted object is restored.