How can i update polymorphic table?

I have an order table with products and some product can have more serial numbers. I can have order id = 1 and product id = 144 with 4 quantity. I need add new or update serial numbers in serial table. How can i create or update serial numbers ?

// Get Used Product ID
    $product = StockProduct::find(144);

// Add serial numbers
    $serialNumber = new SerialNumber;
    $serialNumber->serial_no = '45serial-445';

// Save polymorphic relations
    $product->serialNumbers()->save($serialNumber);

Now i can get order->Product() and with loop get serial numbers. But how can i use save with create or update ?

$product->serialNumbers()->save($serialNumber);

or how can i delete all serial numbers from morph table ? using product id ?

via Chebli Mohamed