To close a bank account on behalf of someone who has passed away, you must have legal authority to manage the account. "Letters of Office" is not really a letter.If a relative is a sole owner of a bank account, the account will likely be closed upon their death. Get an executor checklist to help with settling an estate. Learn what government programs to notify when a loved one dies. My dad passed away two months ago. Got the death certificate in hand and went to the bank to close his account. Enter the 6 letters or numbers shown within the image above. Letters are not case-sensitive. The affidavit is often coupled with a copy of the death certificate.