Revoking a POA and issuing a new one to follow up on a case

I am a Bahraini national and have a Dubai residence visa also (Emirates ID I mean).

I have registered a case through one of my staff at Dubai police and was being updated on developments by this staff. However, he has resigned and is unreachable, and the Dubai police will update/pass information only to that person.

Can I give someone else an authorization letter stating that he can represent me and my offices/properties and that the previous person no longer represents me?

Please help me with your valuable advice!