Make a selection of sales invoices that you want to delete. See [Processing functions].
Troubleshooting
No, the order will not disappear. But you cannot generate a new invoice with the same order. You will have to enter the invoice manually.
No, you cannot delete an invoice that has already been printed.
Sales Manual > Contents > Reviewing, approving, printing and processing invoices > Deleting invoices > [Sales: Management, Deleting sales invoices]