I think you won't be able to pay for the existing purchasing documents if you end-date a site/address using supplier profile of the iSupplier. Updates to the bank information will have a payment impact as well.
It is always advisable to close the open purchasing documents prior to closing/deactivating a supplier.
You may also perform supplier merge to transfer open purchasing documents to a active supplier and then close/deactivate site, bank etc.
Thanks for replying.
Could you please point to an Oracle document regarding the topic.