i want to customize my single product page schema according to me (by code)

Hello,

Thank you for your query and we are so sorry about the trouble this must have caused.

Please note that you’re using the breadcrumbs that come with Woocommerce, not from Rank Math. If you intend to use Rank Math’s breadcrumbs to ensure they match the information from the schema, please remove the Woocommerce breadcrumbs and install ours on your website.

/**
 * Function to disable WooCommerce breadcrumbs
 */
function remove_wc_breadcrumbs() {
remove_action( 'woocommerce_before_main_content', 'woocommerce_breadcrumb', 20, 0 );
}
add_action( 'init', 'remove_wc_breadcrumbs' );

Here’s a guide you can follow to install Rank Math breadcrumbs: https://rankmath.com/kb/breadcrumbs/#add-breadcrumbs-theme

Lastly, to ensure that Rank Math’s breadcrumbs include the category, please make sure the option “Show Category(s)” is enabled in the Breadcrumbs settings.

Please also make sure that you have already enabled the Primary Category for your products: https://rankmath.com/kb/how-to-choose-a-primary-category/

Let us know how that goes. Looking forward to helping you.