There is no way to disable the USB port(s) in the RealPresence Group Series codecs via software.
The functions that the USB port can be used for include:
RealPresence Group Series shouldn’t have any security issues with its USB ports when its securely configured. If it’s using a security mode and a separation of duties between admin and user roles, especially if external authentication is available, it should be able to mitigate most risks that I can think of and record the activities of whoever is trying to do things with it. Polycom’s implementation of RealPresence Group Series software has met with customers information assurances controls and requirements that a non-authorized user (read as not admin) couldn’t pull logs, update or change software confirmation, or really perform any functions that might compromise the unit.
There are physical devices to secure USB ports such as: <Link to USB securing devices>