How to Hide the "Captcha" Admin Menu

function plt_hide_captcha_code_authentication_menus() {
	//Hide the "Settings → Captcha" menu.
	remove_submenu_page('options-general.php', 'captcha-code-authentication');
}

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

Where do I put this code?