If you have purchased stock that the supplier is no longer going to be delivering, then you need to mark it as Final Delivered therefore closing the purchase order. If you don't do this then the purchase order will remain 'open' as the system is expecting the items to be delivered at some point. Check out the video to see how this is done. A step by step guide can be found below the video.
Steps
In Purchasing , open the On Order screen.
Green select the item(s) you wish to mark as Final Delivered.
Use the Actions button to select Mark Final Delivered .
Confirm in the pop up, the item will be removed from the On Order grid.
Notes/Caveats
This action should only be done on partially delivered items on a Purchase Order, if the whole of the Purchase Order is not being delivered the Purchase Order should be cancelled rather than Marked as Final Delivered