To close a bank account on behalf of someone who has passed away, you must have legal authority to manage the account. How To Fill In an Affidavit of Death.This guide covers some things to look for in a Will and how to proceed without one later. I, the undersigned, applying for probate and for letters in the above estate, being first duly sworn, say that: 1. You'll need the original or certified copy of the appointment letter naming you as the personal representative of the estate along with any additional court-. Online: Use our online form to notify us about a customer's death.