I believe if you'll find the extra applications, like ear training, actually don't take up much storage space so deleting them won't give you much additional space. You'll expend a lot of effort for not much gain.
Does your laptop have an internal SD card reader? I didn't find out this one does until after I used it for a year or longer. If so then you can install the largest SD card the computer can handle to use for additional storage.
Another thought is to use a USB drive.
+++ HERE +++ is another thread where the poster is essentially asking the same question.
RealTrack and RealDrum folders use the most storage space so they are what I'd concentrate on moving to external storage.