When Iam learning songs by ear Iam using the program " Transcribe!" and its very good.
Can somebody tell me how I can remove all instruments and vocales except the guitar, to listen to the guitar better?
it just doesn't work that way unless you've got the original recording session with all the separate tracks.

The frequency content of everything just overlaps too much

you can sometimes remove center panned stuff like vocals though (I think its even in one of the audacity menus)