In general it is possible to perform an action, like shipping, refunding, or canceling, on a part of your order line. However, when the product in question is discounted, you can only ship, refund, or cancel the entire order line.
E.g. when your customer orders two chairs against a discounted price, you can only ship, refund, or cancel both chairs.
Read also:
- Is it possible to adjust an order after it has been made?
- How do refunds work with the Orders API?
- How do I cancel a product?
- What are the possible statuses for an order?