You can cancel an invoice by issuing a credit note.
To create a credit note, follow these steps:
Open the original invoice from the invoice list
Click on the 3 dots (top right)
Select "Create" > "Credit Note"
If necessary, edit the information in your credit note. A credit note will automatically register the total amount of the invoice, so make changes if you only want to issue a credit note for a partial amount.
You should also write the reason for the cancellation in the "Notes" section.
When you’re ready, click the blue "Complete" button.