Completely Disable Comments

add_action('admin_init', function () {

    // Redirect any user trying to access comments page

    global $pagenow;

    if ($pagenow === 'edit-comments.php') {

        wp_safe_redirect(admin_url());

        exit;

    }

    // Remove comments metabox from dashboard

    remove_meta_box('dashboard_recent_comments', 'dashboard', 'normal');

    // Disable support for comments and trackbacks in post types

    foreach (get_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');

        }

    }

});

// Close comments on the front-end

add_filter('comments_open', '__return_false', 20, 2);

add_filter('pings_open', '__return_false', 20, 2);

// Hide existing comments

add_filter('comments_array', '__return_empty_array', 10, 2);

// Remove comments page in menu

add_action('admin_menu', function () {

    remove_menu_page('edit-comments.php');

});

// Remove comments links from admin bar

add_action('admin_bar_menu', function () {

    remove_action('admin_bar_menu', 'wp_admin_bar_comments_menu', 60);

}, 0);