Manually invoicing one or more finalised purchase receipt

In the navigation panel, click on Purchasing then Invoices.
On the left hand side of the screen is a list of all of your Purchase Invoices
When searching for a Purchase Invoices use the transaction number search field to be precise.
Left click into that field and start typing in the beginning of that transaction number.
Click on the sale invoice that you wish to reverse
View the information to ensure that is the invoice you want to reverse
Click on the reverse button from the top panel
Pop-up message box will appear for you to fill in the date