On a clean installation of Moodle 2, I created course with a Folder and added 3 files totaling 168 MB to it. I then deleted the Folder from the course. I measured the size of my data folder and took a screenshot of the files table in my database at 3 points:

1. After uploading the files

2. Immediately after deleting the files

3. After the cron job ran at least once

At all 3 points, my data folder was 170 MB. The labeled screenshots of the files table are attached.

I still have the test installation and can provide access to it if necessary.