Management

add_action( 'admin_head', function () {
	if ( current_user_can( 'update_core' ) ) {
		return;
	}
	remove_action( 'admin_notices', 'update_nag', 3 );
}, 1 );

function snipjar_new_user_notifications( $user_id, $notify = 'user' ) {
	if ( empty( $notify ) || 'admin' === $notify ) {
		return;
	} elseif ( 'both' === $notify ) {
		// Send new users the email but not the admin.
		$notify = 'user';
	}
	wp_send_new_user_notifications( $user_id, $notify );
}

add_action(
	'init',
	function () {
		// Disable default email notifications.
		remove_action( 'register_new_user', 'wp_send_new_user_notifications' );
		remove_action( 'edit_user_created_user', 'wp_send_new_user_notifications' );

		// Replace with custom function that only sends to user.
		add_action( 'register_new_user', 'snipjar_new_user_notifications' );
		add_action( 'edit_user_created_user', 'snipjar_new_user_notifications', 10, 2 );
	}
);

add_filter('screen_options_show_screen', '__return_false');

function snipjar_clean_wp_dashboard()
{
    remove_action("welcome_panel", "wp_welcome_panel");
    remove_meta_box("dashboard_primary", "dashboard", "side");
    remove_meta_box("dashboard_secondary", "dashboard", "side");
    remove_meta_box("dashboard_quick_press", "dashboard", "side");
    remove_meta_box("dashboard_recent_drafts", "dashboard", "side");
    remove_meta_box("dashboard_php_nag", "dashboard", "normal");
    remove_meta_box("dashboard_browser_nag", "dashboard", "normal");
    remove_meta_box("dashboard_site_health", "dashboard", "normal");
    remove_meta_box("health_check_status", "dashboard", "normal");
    remove_meta_box("dashboard_activity", "dashboard", "normal");
    remove_meta_box("dashboard_right_now", "dashboard", "normal");
    remove_meta_box("network_dashboard_right_now", "dashboard", "normal");
    remove_meta_box("dashboard_recent_comments", "dashboard", "normal");
    remove_meta_box("dashboard_incoming_links", "dashboard", "normal");
    remove_meta_box("dashboard_plugins", "dashboard", "normal");
}
add_action("wp_dashboard_setup", "snipjar_clean_wp_dashboard");

function hide_admin_notices_except_specific_admin()
{
    //Checking if user is on an admin page
    if (is_admin()) {
        //Getting the current user object
        $current_user = wp_get_current_user();
        //Checking if the current user has the 'administrator' role and their username is not 'specific_username'
        if (
            in_array("administrator", $current_user->roles) &&
            $current_user->user_login !== "INSERT_USERNAME"
        ) {
            //Removing all actions of 'admin_notices'
            remove_all_actions("admin_notices");
        }
    }
}
//Calling the function on 'admin_init' action
add_action("admin_init", "hide_admin_notices_except_specific_admin");

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('init', function () {
    if (is_admin_bar_showing()) {
        remove_action('admin_bar_menu', 'wp_admin_bar_comments_menu', 60);
    }
});

Prevent WordPress from requesting confirmation of the administrator email address upon login.

add_filter( 'admin_email_check_interval', '__return_false' );

After a user resets their password, do not send the notification email to the site administrator.

remove_action( 'after_password_reset', 'wp_password_change_notification' );

add_filter( 'auto_core_update_send_email', '__return_false' );
add_filter( 'auto_plugin_update_send_email', '__return_false' );
add_filter( 'auto_theme_update_send_email', '__return_false' );

add_filter( 'auto_update_theme', '__return_false' );

add_filter( 'auto_update_plugin', '__return_false' );

add_filter( 'auto_update_core', '__return_false' );