Closing Orders
Statuses
To close an order, click the light blue Close Order button or set the order to "Closed" status.
An order can only be closed once every line item is Returned, Lost, Damaged, Sold or Canceled. The Close Order button appears on "Returned", "Returned Late" and "Returned with L&D" orders once they've been invoiced (and, for "Returned with L&D", once the L&D order exists). "Assets Only" and "Maintenance" orders are never invoiced, so they show it right away.
"Sales Only", "Loss & Damage" and "Security Deposit" orders don't have a "Closed" status.

Similarly, once an Invoice is in "Paid", "Void" or "Uncollectible" status, then it is closed or completed. See Invoice Statuses for what each one allows.
Archiving
You can't "archive" orders or invoices either, since you'll often need to refer back to them and aggregate them in various reports. Unless you delete an order or invoice, it hangs around for life.
Canceling and Deleting
Cancel Order and Delete Order are in the order menu.
- An order with a payment, or on an invoice, can't be canceled or deleted. Clear the payment or remove the order from the invoice first. An order on a "Void" invoice can still be canceled.
- Canceling an order also cancels its linked Extended Rental and L&D orders, and deleting an order also deletes its L&D orders, so those linked orders have to pass the same check.
- An order with Extended Rental orders can't be deleted.