Have your network admin deny the user access to the network folder where the
file resides, or only give the user Read Only rights. Personally speaking,
it believe it would be easier to control this at the network level than from
within Excel.
I agree with Kevin's assessment. Even if you password protect a file, there
are so many code-breakers out there it's not even funny. Not to mention, if
the person has full network access, they could still just delete the file.
If you got fellow employees doing that kind of stuff to you, perhaps you
should find a different place of employment?