To understand you, you want to Delete the Deleted files permanently?
If your Answer is YES, sorry,then this is not a feature for our product yet. We have put a feature request in for it.
(the deleted files takes space on the account for a short time then due to a process that runs it could take up to 24 hours to re-calculate storage size.)
You have this option to remove your copy data from the copy folder while retaining a copy it in the cloud:
I was under the impression that when you delete files, it stores them for 30 days and they are purged, thereby freeing up space?
If so, I deleted files several months ago, so past the 30 days, but they still have not purged.