disable comments in WordPress via the functions.php

// Disable support for comments and trackbacks in post types
function disable_comments_post_types_support() {
remove_post_type_support('post', 'comments');
remove_post_type_support('page', 'comments');
}
add_action('admin_init', 'disable_comments_post_types_support');

// Close comments on the front-end
function disable_comments_status() {
return false;
}
add_filter('comments_open', 'disable_comments_status', 20, 2);
add_filter('pings_open', 'disable_comments_status', 20, 2);

// Hide existing comments
function disable_comments_hide_existing_comments($comments) {
$comments = array();
return $comments;
}
add_filter('comments_array', 'disable_comments_hide_existing_comments', 10, 2);

// Remove comments page in menu
function disable_comments_admin_menu() {
remove_menu_page('edit-comments.php');
}
add_action('admin_menu', 'disable_comments_admin_menu');

// Redirect any user trying to access comments page
function disable_comments_admin_menu_redirect() {
global $pagenow;
if ($pagenow === 'edit-comments.php') {
wp_redirect(admin_url()); exit;
}
}
add_action('admin_init', 'disable_comments_admin_menu_redirect');

// Remove comments metabox from dashboard
function disable_comments_dashboard() {
remove_meta_box('dashboard_recent_comments', 'dashboard', 'normal');
}
add_action('admin_init', 'disable_comments_dashboard');

// Remove comments links from admin bar
function disable_comments_admin_bar() {
if (is_admin_bar_showing()) {
remove_action('admin_bar_menu', 'wp_admin_bar_comments_menu', 60);
}
}
add_action('init', 'disable_comments_admin_bar');