Many programs will enable you to do this. Whatever it is, it'll need the chroma keyer effect, which is easy to use and manipulate in Sony Vegas. What you'll need are two layers- on the top, your video and just below that a solid black color (yeah, if you leave all the tracks below that empty it'll be black anyways, but it's safer this way). Add chroma keyer to the top track and get a sample of the color you want to remove. Play around with the settings a bit, and see where it looks best.
