Brave saving banking info - can't delete

How can I tell if it’s the site saving the info or Brave?
I don’t have an “account” at that site. Intuit Quickbooks is a way to send people invoices, and “anybody” can pay them as long as they enter banking or credit card info. When I went to that site the second time, the banking info was blank, but as soon as I clicked in the space to type it, the account number showed up in a one-item drop down menu.
Now that I think about it, when I fill out forms at my own company’s website for purchase orders, the autofill info for individual items (like account numbers, product type, etc) are also there, and I don’t see a place in Brave for those either. Hmm, I guess I need to learn more about how autofill in web browsers works…