private function removeDefaultPrices(Product $product)
    {
        $defaultPrices = [];

        // get default prices
        foreach ($product->getPrices() as $price) {
            if ($price->getId() === null) {
                $defaultPrices[] = $price;
            }
        }

        foreach ($defaultPrices as $price) {
            $product->removePrice($price->getEntity());
        }
    }