User encounters an error when trying to remove a robot from the left panel list in IM.
This is general information applicable to most UIM versions.
Issue is found in older IM client versions.
To get around this, remove the robot using the hub Configuration GUI (instead of from the list on the left panel of Infrastructure Manager).
To do this, double click on the hub probe. Navigate to the Robots tab, highlight the target robot, and then right click -> 'Remove' the robot.
Newer IM versions should allow you delete probes from the left panel. Use the hub GUI as an alternative.