Oh ... my ... f***ing ... word ... Stay the blue freakin' HELL away from the program named Audacity. It is the most unstable P.O.S. audio editor (or maybe even an excuse for one, since it's also damn slow for a "simple" audio editing app) that I've ever used. When I used v1.0.0 in 10.1 (and I think a little in Jaguar), most often, the program crashed if I performed two operations in less than 1.1 or 1.2 seconds. Such operations would be selecting a point in the waveform, then clicking on the menu at the top of the screen. So more than 50% of the time I used the program (from double-clicking it, then quitting it), I had to force quit the f***er. Thus, I completely refuse to touch that program ever again. So be at least halfway helpful to yourself and grab Sound Studio (get the 2.1.1 beta, it's much more stable than 2.1 final).
Now, removing lyrics may or may not be possible. Every time I want to edit out something, I look for an area of the song that has already been provided (such as a back beat or real quick sound effect overlapping) and do a copy and paste (not a cut and paste, I copy the part of the song I think will work) over the lyric that I want to "remove." Now, this is a fairly tedious trial and error process, because not only does the beat have to flow perfectly (every audible beat and all audible rhythm must flow in perfect synchrony), but also (A) the part of the audio clip that you paste (saved to the clipboard) to the part of the waveform where the lyrics is can't be too much louder or quieter than the waveform around it, and (B) the copy/paste content can't have more/fewer beats going on at the same time. Failure to comply with any one of these three conditions will make the paste-over highly obvious to the listener and offending to the audiophile.
In some cases, in which these is no way to make the paste-over perfect, then you are screwed. So enjoy Sound Studio.