We recommend starting from QuoteMachine as you will be appropriately redirected to your Lightspeed Retail Sale. Once you have completed the steps in Lightspeed, you will then be able to finish in QuoteMachine.
If you're looking to void a specific payment, that is explained right here.
Locate the invoice you wish to void
Click Invoices from the left-hand menu
Search for and click on the Invoice
Click Void from the bottom-left
Click on the Lightspeed Retail Sale
You will then be redirected to its matching Lightspeed Retail Sale.
Void the sale in Lightspeed Retail
Click Void Sale from the transaction menu
Click the Void Sale button at the bottom
Click the Void Sale button from the warning menu
Void the sale in QuoteMachine
Close the Lightspeed Retail tab to return to your QuoteMachine Invoice
Click close on the Void invoice pop-up
Click Void from the bottom-left
Click Void from the Void invoice pop-up
If there are any payments on the invoice, you will then be asked what you wish to do with them.