I suggest using a Erase Beyond Recovery tool , like CyberScrub.It is the one I am using and it is very very good.I have the same problem and the program does wonders.It frees up about 2 to 5 GB of HDD space.
The using of HDD space is because of the fact that Windows actually holds everything that you have "removed" on your HDD.It is stupid , I know , but it does that for System Recovery and other programs.Moving the slide bar to a lower level in the System Recovery menu won't do the trick.Use CyberScrub and I guarantee that it will free up a lotta space on your HDD.
Remember : It's not your fault , it's Windows'.
Bye