Want to know how to write a retirement letter of resignation? Get the insights you need and free retirement letter template to help guide the way.Advise your department as soon as you are ready but provide a resignation letter at least 30 days prior to your retirement. Your retirement resignation letter should begin with a header that states the contact information of the sender and addressee as well as the date. How to Write a Retirement Letter Due to Retirement? Section 1: Complete the form and submit to your supervisor for further processing. Select One: â–¡ Adjunct (Hourly Academic). Use one of our resignation letter templates. 4100 Normal Street, San Diego, CA 92103. For the recipient, include their name, title and the employer name and address.