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. In the opening paragraph, clearly state that you are resigning from your position.A resignation letter should be written at least 30 days prior to the effective date of resignation. Add contact details, company name, and date. I recently got hired in a new district and am extremely excited. Do I need to call my principal and department head to resign or is an email ok? Learn how to write a professional resignation letter with our step-by-step guide, easy to use templates and helpful tips.