This is done via the powershell on a local XenDesktop Controller with the following commands:
>asnp citrix.*
>Get-BrokerDesktopGroup -name “Name of RemotePC Desktop group”
## note the “DesktopGroupUID” ##
>Get-BrokerPrivateDesktop -DesktopGroupUid UIDofRemotePCDesktopgroup | Set-BrokerPrivateDesktop -PublishedName “New Name”