Hope you found an answer. In audacity software you can do so , it's within the effects tab, mouse down alphabetically. Anyway - I found it does well if the particular voice to be "removed" is in choral or high stereo. It seems less effective as an effect if it's a center panned vocal.

Sorry so late.  The angles should have no difference. There are all kinds of right angles in electronics / components / and especially in circuitry including non digital. If you take apart the chassis of a analogue component / amp, you will find the leads that come out from the teeny amplifier...