How to Hide Captcha.eu Admin Menus

function plt_hide_captcha_eu_menus() {
	//Hide the "Captcha" menu.
	remove_menu_page('captcha-eu');
	//Hide the "Captcha → Overview" menu.
	remove_submenu_page('captcha-eu', 'captcha-eu');
	//Hide the "Captcha → Settings" menu.
	remove_submenu_page('captcha-eu', 'captcha-eu-settings');
}

add_action('admin_menu', 'plt_hide_captcha_eu_menus', 21);

Where do I put this code?