Hide fields from order emails

I am trying to hide the fields I have added from a customer’s order email. They are hidden field types and are only for our internal use, they also clutter the email are there are several per product.

I did find the code below on the forum, but it is not working for me.

add_filter( 'woocommerce_email_styles', 'add_css_to_emails', 9999, 2 );
 
function add_css_to_emails( $css, $email ) { 
$css .= '
     .wc-item-meta .wc-item-meta-label{ display:none }
     
';
return $css;
}

I placed this code in my functions.php file. Is this the correct area? I tried adding to my themes custom css area, but received several warnings about possible fatal errors.

Thank you for any help on this.