What procedure did you use to delete all of your projects out of your current library? Did you delete the events, too? Did you relocate your projects by copying your current library and placing it on a different drive (my choice), or did you create a new library and move your old projects into it? Did you do a File/Consolidate Library Media before moving/copying the library to a different drive, to make sure that all media goes with it?
Since your iMovie library in the Movies folder still shows that it holds 36 gigs, that would mean that your media is still in the Original Media folder. If you copied and relocated your current library with the projects in it, and have consolidated it beforehand, you can just delete the old library. That should remove the 36GB from your computer.
-- Rich
