As PCBs are customized products, the orders can't be canceled after payment. But we have suggestions for you as below.
1. If the orders are not paid, you can delete the order or contact your sales representative to change the Gerber files or other details.
2. If the orders are paid but don't start to produce, please contact your sales representative. Maybe the orders can be canceled.
3. If the orders are in production, we can't cancel the order. You can contact your sales representative to hold the shipment to save shipping costs.