Sales credit notes are the same as a sale, but with negative item quantities.
Creating a credit note
To create a credit note, either start with a blank sale, and ensure that you enter negative item quantity, or else when in a sale, click "clone to credit" from the "more" drop down menu button.
When this credit is "invoiced", an SC-12345 reference will be created and the balance will be applied to the customer account. Note that it won't be automatically allocated against an invoice (even if you've cloned the invoice to a credit) - so you will probably want to visit the customer payment allocation screen to balance the two against eachother.
Deleting an invoice
You can't delete an invoice, since you have entered transactions into your accounts, and a Tax Invoice has been generated. To conform with tax regulations, you need to reverse the invoice (create a credit note) and then re-invoice.
