Getting Google Drive space back


I have used Dropbox for awhile now. What I like is I can remove (delete) unneeded files and then just get my quota back (space).

Working with someone now who uses Google Drive. If he or I share files on Google Drive…when all done and when the folder is unlinked (unshared), and the "owner" is changed and I do not need it. When that happens the files go away in my Google Drive…but my quota (space) stays the same…?

Even with those files not shared and not visible in my Google Drive on my mac…my space does not go down?