Voiding cancels an unpaid invoice so it no longer needs to be collected. It's permanent and can't be reversed.
Void an invoice
Open the invoice from the Payments menu, or click its row in any invoice list.
Open the actions menu (three-dot menu) and select Void.
Confirm. The invoice is voided immediately.
Voiding is permanent. A voided invoice can't be un-voided — you'd need to issue a new one. Only unpaid invoices can be voided.
Void vs. the other invoice actions
The actions menu has several options that look similar. Pick the right one for your situation:
Void — the invoice shouldn't have been sent, or it won't be paid. Cancels the invoice. Use for: wrong customer, wrong amount, sent in error.
Mark as uncollectible — you know the invoice won't be paid (customer left, dispute settled, etc.) but you want a record of the attempt. Same practical effect as void; different accounting signal.
Mark as paid — the customer paid outside 360Player (cash, bank transfer, etc.) and you want to record the invoice as settled.
Refund / Mark as refunded — for invoices that were already paid and the money needs to go back to the customer. See Refund a payment.
Delete — completely removes the invoice from records. Voiding is usually preferable; it keeps the paper trail intact.