If you have Connector Protection enabled, you would need the password to stop the service. -Matt

It should be automatically removed if you upgrade to 8.4.4 or higher. If you're on a lower version and can't upgrade yet, you can stop the Secure Endpoint service and delete the folder if an old version exists. Thanks, -Matt

There are likely some registry entries still lingering. TAC has some scripts they can provide to help remove those, so please open a case. Thanks, Matt