Top right of the song chart is Send menu icon>Song as midi.
It will have the tracks (separated) of the 3 instruments (the drum one will not map directly to standard midi drum sounds) and you will be able to delete or edit using notation software (like Sibelius or Finale) or a DAW (Apple Logic etc.)
Note: it creates the midi file from the settings the player has at the time, so set key, chorus, tempo, style etc. before making the file.