Is it possible to change the vendor a Purchase Order was assigned to?

Hi Crystal:

Thank you for your query. 

If a purchase order has been created for the wrong vendor, best practice would be to cancel that Purchase Order and issuing a new Purchase Order to the correct Vendor. For further details please refer to this article. https://fc.force.com/customer/s/article/Purchasing-Inventory-Purchase-Order-Center

Best,

Rene’

Fourth  

Thank you Rene. If you delete a Purchase Order do you need to resubmit a requisition and go through the approval process again, or will it just kick the requisition back to requisition center when the PO is deleted?

To respond to your follow up, Cancelling the PO cancels the entire transaction, PR to PO. You will have to recreate the requisition.

Best,

Rene'

Fourth