getting rid of an A/C buzz.

I remember seeing a LAFCPUG meeting on Soundtrack Pro, where the tech sampled a small section of some audio/video footage that had a bad hum in in... then just clicked a few buttons and REMOVED that particular soud from the whole clip. For the life of me, I've clicked everybutton in Soundtrack Pro and can't figure out how he did it. It was hum reduction, he sample and removed it. I've got the same problem but with an Air Conditioner hum (from 50 feet) away, that we thought wouldn't be a problem....but that ended up sounding worse in playback.