Sales Orders and Purchase Orders can only be cancelled - not deleted. This is so that it is possible to refer to past documents and sort out any issues or inconsistencies that may arise later.
In order to cancel a Sales/Purchase order, the following conditions must apply:
The Sales/Purchase Order must not be closed
An invoice/shipping document that is generated against the Sales/Purchase Order must also not be closed
If the Sales/Purchase Order is Closed. You might be able to re-open it based on the access permissions you have been given. See: http://help.megaventory.com/en/articles/3379949-how-to-revert-a-sales-order-status-from-closed-to-invoiced
The following instructions are provided for Sales Orders but similar steps apply for Purchase Orders.
In order to cancel a Shipped and Invoiced Sales Order you first need to cancel the documents you have issued.
In the Sales Order you wish to cancel, go to the Related Documents tab and open all the Related Documents by clicking on their name:
2. For each document click on More > Cancel Document:
3. Go back to the Sales Order you wish to cancel from the Sales Order list or from the Related Documents tab. It will be now in the Approved state again and you will be able to cancel it under the More menu, by clicking on Cancel Sales Order: