Some of our moodle users inserted a file in html editor. They highlighted some text, then choose link, it asked them to provide URL, see the attached img1. if you clicked the file icon, it will bring you file picker that you can upload a file. Then it will have a link to the file like http://yoursite/pluginfile.php/2875/course/section/123/yourfile.pdf.
In the database, in table mdl_files, it showed the record, filearea is section, component is course.
My users wanted to remove the files from the server, they deleted the link. however, the file is still on the server. I checked the database, the record is still there.
The problem is my user accidentally uploaded some confidential files, they wanted to delete them from moodle site. There is no way we can delete them. They deleted the link for days. The files are still there. If user bookmarked the link to the file, they can still access it. Unfortunately, the file even searchable through google.
If any one knows how to remove such file permanently, please let me know.