Once stock has been dispatched (shipped) on a Sales Order, it cannot be undone. Instead, you will need to complete an invoice for the dispatched stock and then create a Credit Note to return the sale and stock back to your inventory, reversing the transaction.

If the stock is still due to be shipped but at a later date, use the Clone function in the Sales Order's Order dropdown menu to efficiently re-create the original Sales Order and re-dispatch the stock as and when required. For more details see, How to clone a Sales Order.

Reverse dispatching stock that hasn't been invoiced

When a Shipment's been incorrectly dispatched for a Sales Order, you can reverse this and bring the stock back into your inventory using the following steps.

Complete an Invoice for the dispatched Shipment

1. In the Sales Order that's been dispatched but not yet invoiced head to the Shipments tab.
   
   
   
2. In the Shipment tab, hover over the Action Cog on the shipment line and select Create Invoice.
   
   
   
3. Complete the Invoice.

Create a Credit Note to credit and return the dispatched stock

1. Go back to the Sales Order and in the Invoices tab, hover over the Action Cog for the newly completed invoice and select Credit.
   
   
   
2. A new Credit will be created, populated with the invoiced stock. Tick the Return checkbox for the Credit Lines to ensure the stock is returned to your inventory. 
   
3. Click Complete in the Credit Note and the invoiced stock that was shipped on the Sales Order will be returned to your stock on hand to sell or user again.

For more details on completing credits, see How to process a Credit Note.