Disable mandatory standard field for frappe hosted site

I am trying to import data from an old ERPNext system. Since we are a business that sometimes gives goods on credit, we usually can submit the invoice on the POS and it will submit as unpaid and later change to overdue. This lets us filter our invoices as unpaid/overdue for accounting or taxes purposes. But with the import, the new update is saying their must be a mandatory payment method even though they are not paid. I cannot select a payment method as the client decides how to pay when they eventually come to pay it. However, we like to input the sale on the day it happened so that stock-taking and accounting is easier then update it by inputting a payment entry when paid. Is there an ERPNext expert on this forum who can advice?
I have seen a lot of posts on disabling mandatory fields and they all say to hide it. But mandatory standard fields cannot be hidden.
This seems like a very bad update since a business decides what is mandatory for standard for them on a case by case basis. Plea

You can create One Payment Method - “Credit” and use that for this Invoices.