Completely disable any commenting and trackback features in WordPress. This code won’t turn off any “This post has X comments” or front-end code that displays comments that may be in your theme. Instead it removes the ability for comments to be added/stored against posts.
Source: https://keithgreer.uk/wordpress-code-completely-disable-comments-using-functions-php
// First, this will disable support for comments and trackbacks in post types
function df_disable_comments_post_types_support() {
$post_types = get_post_types();
foreach ($post_types as $post_type) {
if(post_type_supports($post_type, 'comments')) {
remove_post_type_support($post_type, 'comments');
remove_post_type_support($post_type, 'trackbacks');
}
}
}
add_action('admin_init', 'df_disable_comments_post_types_support');
// Then close any comments open comments on the front-end just in case
function df_disable_comments_status() {
return false;
}
add_filter('comments_open', 'df_disable_comments_status', 20, 2);
add_filter('pings_open', 'df_disable_comments_status', 20, 2);
// Finally, hide any existing comments that are on the site.
function df_disable_comments_hide_existing_comments($comments) {
$comments = array();
return $comments;
}
add_filter('comments_array', 'df_disable_comments_hide_existing_comments', 10, 2);