Below is a sample union resignation letter. You should check your union's constitution and bylaws to see if it is specific to whom a resignation must be sent.How to write a resignation letter that's effective immediately? I will go over a step-by-step resignation template letter you can use, how to structure it and provide examples of resignation letters. Welcome to Chicago Resume Expert for Resignation Letter Writing. Many times it is difficult to resign diplomatically and tactfully. Please accept this letter as a notice of my resignation. How to Use a Police Officer Resignation Letter (5 steps). Notify the Chief of Police; Give Reasons; Date of Resignation; Submit Letter; Return Items. 1. How to Use a Police Officer Resignation Letter (5 steps).