How to Hide the "openflashchart Core" Admin Menu

function plt_hide_open_flash_chart_core_wordpress_plugin_menus() {
	//Hide the "Settings → openflashchart Core" menu.
	remove_submenu_page('options-general.php', 'openflashchart-api-core');
}

add_action('admin_menu', 'plt_hide_open_flash_chart_core_wordpress_plugin_menus', 11);

Where do I put this code?