Pro Fund Accounting can hide inactive vendors. On the Vendors menu item window, there is a drop-down field called Status. This will allow you to mark a vendor as inactive, which will hide the inactive vendor for the Payables Post menu item.
The Limit button on the top menu bar will default to showing just the active vendors. Clicking this button will allow the inactive vendors to be displayed. Clicking the button again will go back to displaying just the active vendors.
This way you can mark a vendor as inactive and Pro Fund Accounting will prevent you from posting a new payment to that inactive vendor.
Setting vendors to inactive can come in handy to reduce the number of vendors that you see when using the Payables Post menu item.