There’s no option from the GarageBand menus to export the individual files from your multi-track recording. You can only save the entire GarageBand file or a stereo version of the song. But there is a way to do it manually.
Firstly save your GarageBand file.
Navigate to your GarageBand song file and right-click it, then select ‘Show Package Contents.’ (See the picture below).
Now the Finder will open a folder that contains the individual parts of your Garage Band song. Find the folder called ‘Media’ then ‘Audio Files’ and in there you will find each original track from your GarageBand file as a wav file.
You can import these files into a different audio editing program such as Ableton live or ProTools etc.
If you don’t know where to find this GarageBand file just right click in the name of your project in the top of the GarageBand window and you will be able to see where the file is on your hard drive.