Hey Eric,

You’ll need to enable Template Path Hints in order to locate the template file that’s being used. I’m confident that it’s a template file and not somewhere in the code. You can also locate the XML path that’s responsible for injecting the PO Number and remove that as well.

The PO Number is used for Level 3 Order Processing in order to get you better rates with your credit card processor. It’s also not a requirement in order to process any orders, so deleting it won’t be a problem.