If for any reason an invoice needs to be canceled, please click the "Void" option. This article explains how to do it. Keep in mind that only the Sales Managers and Admins are allowed to void an order individually. The option to void orders massively depends on a setting per user.
If any item of the order has already been shipped, the order cannot be voided. For voiding the order, use the Return Option with the scan gun in order to receive the product back first and then you will be able to void the order.
If an invoice has already been paid, the payment must be reversed/edited before the invoice can be voided.