Where a Sales Order item has been either picked for dispatch, or dispatched, then the order cannot be cancelled.

However, you can:

• edit the order to delete any order items that have not yet been picked or dispatched, which will effectively complete the order;
• where items have been picked and not yet dispatched, ‘unpick’ these items during the dispatch and invoice process, which means that you can then cancel these items.

Where items have already been dispatched, then clearly these cannot be cancelled, so if not required by the customer you will need to arrange return and create a Sales Credit.