You can cancel an invoice or credit note as long as it has not been posted.
Once cancelled both the order and the despatch notes can be amended, before printing the new invoice. The new invoice is assigned the next available invoice number.
Details of the cancelled sales invoice remain stored in Sage 200. A cancelled sales invoice is removed from Sage 200 if you delete archived sales orders and returns.
You can also cancel credit notes when dealing with a sales return.
When the invoice is cancelled:
Open: Sales Order Processing > Order Processing > Cancel Invoice.