For VendorPay orders, notaries can no longer be removed once they have downloaded docs on an order. Typically if a notary needs to be removed after documents have been sent, it is because the order did not sign and the notary may be owed a fee. For VendorPay orders, we are only capable of sending out a payment to one notary per order, and so we do not allow a notary to be removed after documents have been downloaded.
To assign a new notary you will need to duplicate the original order. You can see the steps for this process and what actions to take on the original order here.