Firstname and lastname greyout or hidden Billing details at next checkout like username is hidden [closed]

Use filter woocommerce_checkout_fields:

add_filter( 'woocommerce_checkout_fields' , 'checkout_change_fields' );

function checkout_change_fields( $fields ) {

     return $fields;
}

more samples https://docs.woocommerce.com/document/tutorial-customising-checkout-fields-using-actions-and-filters/

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)