how to turn off autopay

I went to send an invoice for a single item to a buyer here in the USA and I received the following notice" Items that autopay in 1 hour, involve the vault, require an Authenticity Guarantee, or are exports cannot be shipped together and are not shown."

Bottom line is that I cannot send an invoice for this one stupid vintage postcard I sold.. As a seller I never have requested this so-called "autopay" and I want it to stop.

If anyone can help me, first pretend I am a complete idiot and do so with a screen by screen listing of how to get to the promised land of the page where I can send this autopay option to purgatory where it belongs.