How to Hide the "Crowdsignal" Admin Menu

function plt_hide_crowdsignal_forms_menus() {
	//Hide the "Settings → Crowdsignal" menu.
	remove_submenu_page('options-general.php', 'crowdsignal-settings');
}

add_action('admin_menu', 'plt_hide_crowdsignal_forms_menus', 13);

Where do I put this code?