In reality, you cant. That would be like trying to remove the sugar from a donut. Sure, you can use EQ to reduce the frequencies where the vocals lie, but that is not removing the vocals. What you are doing is removing a big chunk of the frequency spectrum from the music.
"You can't turn a sausage into a trout. It might be a Jimmy Dean but it will never grow fins and swim."
you can get a clean vocal if you have an instrumental version of the track in question --- you import the instrumental and fulltracks into a daw (make sure they are synced to the exact sample) and then invert the phase of the instrumental -- you should have a clean vocal left
i haven't actually done this myself but i know that this is the technique that is used to make all the 'mash-ups' you hear on radio
there's probably some freeware out there that will do it for you. what it does is listen to both channels, and removes anything that is identical in both channels. since the vocal is usually panned dead center, it will get chopped out.
but often times a cd track will have quadruple-tracked lead vocals panned all over the place, and then the results aren't as good.
For most practical purposes you cant do it. There are tools that are advertised, and some even freeware but the bottom line is with very limited results.
Your best case would be eliminating a vocal that is mixed mono and centered. No reverb involved, no other background voices....then yeah it will work.
But how many songs do you know of where the above is true?
All the processors that I have ever seen worked by canceling the phase of the center information (usually where vocals are placed)
What's done is instead of canceling all of the center, you focus on the frequency range of teh vocals only. THis will of course effect the snr/kick and all other center info in the same freq range as the vocals.
If you wanna play around with it, there's a pretty cool version in the Roland VS 880's etc
Thanks for all the responses! I'm just trying to take all the vocals out of a friggin "Charlie and the Chocolate Factory" CD for a friend. I'll give all these suggestions a go.