A credit note reduces or cancels an invoice you have already sent, for returned goods, an overcharge or a discount agreed later. Enter what is being credited and the total credit adds up.
Once an invoice has been sent, it should not be edited or deleted. A credit note is the correction: it records that the customer owes less than the invoice said.
If the invoice was made here, open it and use “Make a credit note”. Then remove the items that are not being credited, or lower the quantities.