Can I change the payment terms on a requisition as a Purchasing Manager with editing abilities?

Members of the Purchasing Manager group are unable to edit/delete payment terms. Membership in either the Payment Manager or Procurement Manager or Purchasing Agent group is required. Members of these groups would get Procure-to-Pay Manager functions under Core Administration.

Note: Since the October 2015 release, members of Procurement Manager or Purchasing Agent groups are able to edit Payment Terms on Requisition creation screen.

What is important to notice is the fact that payment terms come from supplier location details. So, if you would like to change payment terms, this needs to be done for the entire supplier location and affects all orders for this supplier location.

Please note that the permission for the groups are provided only if customer is using entitlement of Procure to Pay Basic or Procure to Pay Professional.
In case customer is using Ariba Requisition to Receipt, he will be able to see the Procure to Pay menu, but only with options for Commodity, Part Number and determination rules.

Core Procurement > Core Administration > Core Accounting