Voiding cancels an unpaid invoice so it no longer needs to be collected. It's permanent and can't be reversed.
Open the invoice from Payments > Invoices, or click its row in any invoice list.
Open the more menu (three-dot icon) and select Void.
Pick a Reason for voiding, then click Void invoice.
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 row 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.