To hide shipping lines and details a from admin order single pages you will use the following:
add_filter( 'woocommerce_order_get_items', 'custom_order_get_items', 10, 3 );
function custom_order_get_items( $items, $order, $types ) {
if ( is_admin() && $types == array('shipping') ) {
$items = array();
}
return $items;
}
Code goes in function.php file of your active child theme (or active theme). Tested and works.