good question Andy
Look it very much depends on the PM, but the reason I would give to the
business is that PM's may delete projects that should not be delted. On the
other hand if you control the deletion with an Admin, you have a very clear
defined process that is reproducable.
If you believe that your PM's should delete projects, ( which I would not by
the way
--- no I am not a control freak
) there is certainly no
technical reason why not, it is purly a governance process reason.
You wouldnt give a PM the possibillity to delete postings in your financial
project accounting system either, simply because you need to account for any
changes or deletion. That is essentially the same reason.
I hope this will make it easier for you to justify why ( or why not )
Best of luck mate