How to Hide WP SMS Admin Menus

function plt_hide_wp_sms_menus() {
	//Hide "SMS".
	remove_menu_page('wp-sms');
	//Hide "SMS → Send SMS".
	remove_submenu_page('wp-sms', 'wp-sms');
	//Hide "SMS → Outbox".
	remove_submenu_page('wp-sms', 'wp-sms-outbox');
	//Hide "SMS → Subscribers".
	remove_submenu_page('wp-sms', 'wp-sms-subscribers');
	//Hide "SMS → Groups".
	remove_submenu_page('wp-sms', 'wp-sms-subscribers-group');
	//Hide "SMS → Settings".
	remove_submenu_page('wp-sms', 'wp-sms-settings');
	//Hide "SMS → Professional".
	remove_submenu_page('wp-sms', 'wp-sms-pro');
}

add_action('admin_menu', 'plt_hide_wp_sms_menus', 12);

Where do I put this code?