Void an Invoice
Invoices can be voided if they were entered in error as long as they are not included in a VAT Report or have not been partially or fully paid/credit noted.
Open an existing invoice in View/Edit mode. Use the Sales Invoice options drop down list to select the Void option, which will set all value fields in the invoice to zero.

Click the Save button to void the invoice.
Voided invoices are still visible in the Paid and All Sales tabs, to show that no gaps exist in the invoice number sequence.
