Permission has to be given to a user to cancel a PO, which is provided in SetupHub, User Management, Assign Users to ... Permissions.
The user and app (PurchaseHub) are selected, and:
- cancel all POs - the user can cancel any PO; and, or
- cancel my POs - the user can cancel any PO he or she 'touches' as a requester or approver.
Once permission is given, select the PO in My POs or All POs which will take you to the PO Summary page. Scroll down the page & select Cancel.