Here is a sample general authorization letter template. You can use this to write a wide range of different authorization letters.
(Recipient Name and Address)
Subject: Authorization Letter
To Whomsoever It May Concern
I, (Your Name), hereby authorize (Authorized Person’s Name) to (Detail of authorization, for example: picking up bank documents, sell your car, withdraw money from the bank, etc.) excluding (the things you don’t want to authorize to the person). The authorization of this letter is valid from (Start Date) to (End-Date).
The identity proof of the authorized person is provided below for your verification purposes. Please feel free to contact me if there are any questions.
Person: (Authorized Name)
Identity Proof: (Passport, ID)
Signature: (Authorized Person)