Hello,
Thank you for your message.
You cannot hide the tray icon itself, it's always there. This is because Remote Utilities is legitimate software for remote administration and support and must reveal itself in the system for the remote user. Otherwise, antivirus/security software may erroneously detect and remove it.
You can, however, hide the tray icon menu. That is, right-clicking on the tray icon won't produce a contextual menu. You can enable it back if you run the Host settings using Windows Start button (or just doing the search "Settings for Host").
Hope that helps.