In Advance Steel 2010 the "DELETE" command will completely delete an element from a drawing. After using the "DELETE" command, a grey box will appear in order to draw attention to the user to update the drawing.
In the case below, the hidden lines located behind the deleted element become visible after updating the drawing. Also, the labels will appear for the elements that have become visible.
To restore the deleted elements you should select the "Restore user - erased parts" option in the properties dialog box of the drawing.