What Darrel is talking about is mastering. The DJ'* usually belong to a "Record Pool" where they are given promotional copies of the new and upcoming music which contain remixes, and instrumentals.
In order to remove the lyrics professionaly, You would need the original DAT tape in order to re-load it into a studio environment. I have a button on my mixer that muffles, not eliminates the lyrics, but its only done on an aux input, not digital like I wish it could be. I could chop the song, take a sample and loop it for you if you'd like