Answer: Purge the files
Explanation: The files mentioned in the question are not required for further use and also do not contain relevant information.It won't help in any future investigation and are not having data which can support other work.
Therefore, such files should be eliminated as they only contain unwanted information. By clearing out the files there would be space for more useful files.
The files should be cleared out in such a manner that it won't be able to provide information to other sources even though data is not accurate because files belong to the intelligence department.