How to Hide MailArchiver Admin Menus

function plt_hide_mailarchiver_menus() {
	//Hide the "PerfOps Settings" menu.
	remove_menu_page('perfopsone-settings');
	//Hide the "PerfOps Settings → Control Center" menu.
	remove_submenu_page('perfopsone-settings', 'perfopsone-settings');
	//Hide the "PerfOps Settings → MailArchiver" menu.
	remove_submenu_page('perfopsone-settings', 'mailarchiver-settings');
}

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

Where do I put this code?