How to Hide Simple Sitemap Admin Menus

function plt_hide_simple_sitemap_menus() {
	//Hide "Simple Sitemap".
	remove_menu_page('simple-sitemap-menu');
	//Hide "Simple Sitemap → Settings".
	remove_submenu_page('simple-sitemap-menu', 'simple-sitemap-menu');
	//Hide "Simple Sitemap → New Features".
	remove_submenu_page('simple-sitemap-menu', 'simple-sitemap-menu-new-features');
	//Hide "Simple Sitemap → Contact Us".
	remove_submenu_page('simple-sitemap-menu', 'simple-sitemap-menu-contact');
	//Hide "Simple Sitemap → Support Forum".
	remove_submenu_page('simple-sitemap-menu', 'simple-sitemap-menu-wp-support-forum');
	//Hide "Simple Sitemap → Upgrade".
	remove_submenu_page('simple-sitemap-menu', 'simple-sitemap-menu-pricing');
	//Hide "Simple Sitemap → About".
	remove_submenu_page('simple-sitemap-menu', 'simple-sitemap-menu-welcome');
}

add_action('admin_menu', 'plt_hide_simple_sitemap_menus', 1000000000);
Where do I put this code?