How to fix hentry error for google search console

Would someone tell me how to fix errors at structured data in google search console?
I have “Missing author” and “Missing updated” errors.

I found the information and added the following code onto functions.php, but this code shows very top of the page and doesn’t work with the theme.

function remove_hentry( $classes ) {
$classes = array_diff($classes, array(‘hentry’));
return $classes;
}

add_filter(‘post_class’, ‘remove_hentry’);

I have now no idea where to fix.
Thank you in advance.