To remove certain audio portions of a particular song, I use an Intelligate that has both a lo & hi pass filter in conjuction with a Aphex para eq (certain graph eq's cannot be tuned to a particular freq'y for boost/cut due to low incremental values or steps).
Upon determining the desired audio signal freq'y which I'm looking to eliminate, say a synth run at 20khz, I slap on the hi-pass filter in that range , then utilize the para to fine tune the cut while boosting any other signal in that particular range that might also be affected via the cut.