A resignation letter should be written at least 30 days prior to the effective date of resignation. Submit a signed letter of resignation to your immediate supervisor, with a copy to your Human Resources Director.You are free to resign with thirty days notice. Check with the union and don't count on what I'm saying but the rule is give thirty days notice. You will first need an approval letter from the Chancellor's Office and a waiver from the COIB. In this article, we'll guide you through the essentials of writing a resignation letter when going back to school, ensuring you leave on good terms. Fill out the form on this page to get a free editable Google Docs template with sample teacher resignation letters to help you compose your own. Add contact details, company name, and date. Why should you write your resignation letter before starting on the job? How did the sinking of the Titanic save lives?