If you have ableton or any similar production software, you need to find the acapella and the regular version that you already have. You put the two tracks at the same time in your sequence, and invert the sound wave of the acapella. The waves of the vocals will cancel out and you'll be left with a workable instrumental.
Keep in mind, you need the vocals to line up EXACTLY for this to work even the slightest bit. And they need to be exact identical vocal tracks, not one recorded afterwards.
If you can't find an acapella, you can also play around with EQs and try to isolate the vocal frequencies and lower those frequencies, but it usually sounds sloppy and doesn't work so well.
If you have more questions, just PM me or write them here.
