How can I create a statement for a customer that is a sub-customer? Do I have to take the customer off the sub-customer or is there a way to do it without that step?

You control the information in the setup of your Customers and Sub-Customers. You can create a statement for either at any time. Some information automatically copies to a Sub-Customer account from the Main Customer account, so you will need to edit the Sub-Customer information so that it flows through to your statement the way you want it to. If the name or billing address are different, update them accordingly.