As you have left the program, double-click on the icon named Rebar to enter it again.
Choose Order->Update/Delete/Print or press F5.
The order header window will appear. Type the number that was assigned before to your order in the Order Code field, and press Load Order.
Your order header data will appear on the window. Press the OK button.
The order detail window will appear.
From the menu choose Edit->Delete several rows.
Now you are in front of the Rows to delete window.
Type 1-9999 in the Rows field and press OK.
All the rows in the order have been deleted. The 9999 is just a number you are sure is bigger than the number of rows in the order, so that all the rows are deleted.
Choose File->Save Order and exit.
The order has been deleted.
Choose option File->Exit to quit the program.