How to Hide the "Crayon" Admin Menu

function plt_hide_crayon_syntax_highlighter_menus() {
	//Hide the "Settings → Crayon" menu.
	remove_submenu_page('options-general.php', 'crayon_settings');
}

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

Where do I put this code?