A Light Probe Group adds one or more light probes to a scene.
A new probe can be created by clicking the Add Probe button in the inspector. Once created, the probe can be selected and moved in much the same way as a GameObject and can be deleted by typing Ctrl/Cmd + Backspace.
Is something described here not working as you expect it to? It might be a Known Issue. Please check with the Issue Tracker at issuetracker.unity3d.com.