I don't quite understand the issue. As far as I know Ornatrix license server will not ask for a password. The loading issue happens in the latest Cinema 4D build. We are developing on build 052, other builds may not work for now while Ornatrix is in beta. We are working to support the latest builds, but in the meantime maybe you can try build 052. 

That being said, to uninstall the plugin just use "Programs and Features" if you are using Windows, or just remove it from the Plugins folder. 

Jeordanis Figuereo (Product Designer. EPHERE Inc.)