You misunderstand the problem. There is no guaranteed method to do this. All the techniques we have depend 100% on how it was recorded. There are only two real techniques that work to some degree. One simply looks for things that are exactly the same on both channels - usually the vocal, but often the bass guitar too - these can then be removed to some degree, however, if the voice has effects on it, as many do, then these effects may not be the same on both channels, leaving the voice missing, but sitting in a 'hole' of reverb and effects. Early Elton John tracks are very typical. You can remove his voice but you leave in a cathedral like reverberation that prevents you using the track - it's like a ghost Elton. The other helpful feature is eq - as you can tweak the recording to do the null out trick above, but only in certain bands. You can buy software that does these things semi-automatically, but the success is down to the recording. How it was recorded in the studio. A voice centre, piano left and drums right would be pretty successful, but once you add compression, hard eq, effects and lots of sound sources, the success rate drops drastically. It's not a trick pro studios can do and amateur ones can't - it's just physics. There are now plug-ins that will reduce reverberation in a recording, something quite recent really, but none of the remove vocals techniques do it without damaging the quality of the track. They're often ghostly, with squashed bass and kick drum, and have some instruments missing, others made artificially loud. If you want to put up the track you want to use on a hosting site, and giving us the link, we'll have a listen and report back if you like? Some of us quite like fiddling with these.