The process is the same for cancelling a sales invoice and a sales credit as both appear in the same list of invoices; either the Invoices tab of your customer or the Projects Invoices screen.
You can cancel a sales invoice after it is produced but note that the invoice number will be removed and will not be re-used. Your accounts department may prefer that you create a credit note to rectify the problem.
- Go to the customer window or the projects window to view a list of invoices.
- Locate the invoice you need to cancel
- Right-click on the invoice number
Select Cancel Invoice/Credit from the popup menu - Confirm by clicking Yes
Once the invoice has been cancelled your sales order remains, so you could continue editing it and/or create a new invoice later.