You cannot de-register or remove a Symantec Proxy Security Gateway (ProxySG) or Advanced Secure Gateway (ASG) appliance device that is associated with a location in the ThreatPulse Portal just by clicking remove. You must telnet into the ProxySG appliance and run a couple of commands before you can remove the device from Web Security Service (WSS) Portal.
To de-register at any time, telnet into the ProxySG appliance
#(config cloud-service) deregister
If you encounter connection errors while trying to de-register, enter