Here are 3 examples that you can use for resignation letter as Assistant Professor -. This is to inform you of my intention to resign.My last day of work will be (DATE). Advise your department as soon as you are ready but provide a resignation letter at least 30 days prior to your retirement. You'll have to submit a formal resignation letter. Your resignation letter should be short and only include your official title and when your last day will be. Resignation letters should use the formal greeting: "Dear". The first sentence in the letter should state that you are resigning and when. The information contained below provides additional information about a layoff, resignation or retirement. Expand All. Layoffs.