This module will allow you to edit an order in your admin section.

PLEASE NOTE:  Just because you edit an order, does not mean it is going to change the amount that you received for the order - either by crediting the customer or charging them more. 

Works with Zen Cart Version 1.3.7, 1.3.8, 1.3.9, 1.5.0, 1.5.1, 1.5.3, 1.5.4, 1.5.5