Deleting public files - not really deleted from public view?

Deleting public files - not really deleted from public view?

I deleted some powerpoint files that I created/uploaded. They do not appear in my file list. However, others have told me these files are able to accessed by others. This is very serious.
Let's say there is a copyright issue and I find out that these files should not be viewable or accessible. I then delete the files. They should disappear COMPLETELY from everyone's view once I delete them. They may still have been copied by some but the point of deletion should prevent any widespread use of those files from that point on. This delete action would minimize the damage.

IS it a true statement? If so, how to remove those files from zoho then?

Thank you.

Tom