As per provided privileges from eZee Optimus back base on Outlet and User level system allow to approve or reject purchase Order.
1) Add purchase order from the Purchase Order tab from the inventory section.
2) Select that purchase order and approve or Reject it from the right bottom.
3) You can see the Purchase order status as per screen shot.
Do visit on live chat support if you have any further queries for the eZee Optimus.
eZee Optimus Live chat Support