If you happen to have many targets (target - computer/boards that runs Neutrino)
it clutters the target navigator and other tools when you need to select one.
You can "deactivate" ones you are not using - to do that open Navigator view (Window->Show View->Other...->General->
Navigator)
and you can see your targets as projects there. Select ones you want to de-activate and close them 
(right click and select Close Project). 
If you now switch back to Target Navigator it would be gone from the list.
To re-active select Open Project from Navigator view.