Toggle the constellation lines on and off using View/ Show Constellations. You can configure constellation colors using the Options/ Colors dialog box.
Why Stars and Constellations?
There is no doubt about it, there are better programs out there for displaying the optical sky than Radio Eyes. So why do we bother displaying stars and constellation lines in a program that is supposed to be about the Radio Sky? The answer is that it allows us to orient ourselves using these guideposts that humans (and maybe other animals) have used for thousands of years. Even if your knowledge of the optical sky is limited (as is mine), you probably can recognize a few constellations. Suppose you want to do a drift scan of Cygnus A, a very strong radio source. You set everything up, print out a Tracking Table and a Meridian Drift Scan Table. A couple of hours before the observation, you go out to set the elevation of the antenna and looking up into the clear dark sky you can see no sign of the constellation Cygnus! Ahh! You run back inside and see you have set your longitude wrong by 180 degrees in Radio Eyes! You are 12 hours out of sync with the universe.
So you see the optical sky can be very handy to radio astronomers. When Jupiter was discovered as a radio source it was spotted optically to be in the beam of the antenna! If you don't like the features like stars and constellations, turn them off.