We have a requirement from a client to protect the database our application uses, even from their local administrators (Auditors just gave them that requirement).
In the
Auditors always ask for this, like they ask for other things that can never be done.
What you need to do is put it into risk-mitigation terms and show what controls you do have (tracking when users are elevated to administrators, what they did and that they were de-elevated afterwards) instead of in absolutes.
I once had a boss ask for total system redundancy without defining what he meant or how much he was willing to pay and sacrifice.