This article will address how to write a retirement letter of resignation and provide an example that you can use as a template for your own retirement letter. Specify the date of your retirement.Retirement resignation letter. There are many reasons you might be leaving such as: a new job, family, medical, retirement, or personal. Therefore, agencies should require the employee to submit a written letter of resignation before they process the VRS Refund Request Form. What's included in a retirement letter of resignation?