I'm not sure if you can remove a song from All Tracks without removing it from PlayIt Live entirely, but to add a track to a different track group go to "Manage > Track Groups...", select the track group you want to add the track to, browse for the track on the left side of the window (this lists all your tracks) and press the > button to move the track over to the right side (which lists tracks in the group).
JP McCartney
Can I move a song from the All Tracks to a different category? I have a couple of songs that loaded into my all tracks and not my oldies library.