Disable User Registration/Log in

After the customer has purchased an image, they land on the receipt page (as well as having a receipt emailed to them).

At the bottom of this page is a form where they are asked to enter their email address to register and a password will be emailed to them to enable them to log in later to. Something like this…

“Log in below or register to gain access to your purchased images”

As my images can’t be downloaded (they are sent by email), how can I disable the function of them registering?

Thanks

http://wordpress.org/plugins/image-store/