how to use custom checkout field in code

am using WooCommerce and I have a custom checkout field in form of a selection list. I am trying to remove COD gateway, when customer select on a custom checkout field a specific option (“newyork” in this case).

Here below is my actual code where I don’t know how to make the IF statement condition part working:

add_filter(‘woocommerce_available_payment_gateways’, ‘woocs_filter_gateways’, 1);

function woocs_filter_gateways($gateway_list)
{
if ( order_meta key=”wc_billing_field_7378″ value = newyork )
{
unset($gateway_list[‘cod’]);
}

return $gateway_list;
}
How can I get the selected value of my custom checkout field In my code, to get my IF statement working?