Thanks for posting!
You can delete contacts in the software by hovering over them > click the "V" arrow > Click the "Settings" cog > Delete.
However, if you mean the "Unnamed Devices", these are the last ID's you connected to that were not in your contacts list and unfortunately these cannot be removed. But they will change as you connect to more devices.
Any reason why these stale records cant be deleted? Seems a bit strange there is no process for housekeeping and keeping the Management Console as tidy as possible, as can be achieved in most if not all other Asset Management and Support tools. When rolling out and replacing hundreds or thousands of devices there will be a massive ammount of dead-wood.
Are there any plans to enable this?