Obviously you cannot remove a file from a middle of the media. But I
suppose you want to scratch the whole media.
The only way I see would be to manipulate the database directly.
Question is do you know which files are those. If you do, I suppose the
way to do so would be to remove the entries from the "job" table (you'd
have to join the file and path entries to pinpoint the files to delete).
_Probably_ (I haven't tested that but that's what I deduce from the
database structure), you could find which files were on that particular
media file by correlating the fileindex field from the file table for a
given job with a jobmedia table (firstindex and lastindex field).
But of course test before applying in prod.
MK