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. 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. Add contact details, company name, and date. A resignation letter should be written at least 30 days prior to the effective date of resignation. Learn how to write a professional resignation letter with our step-by-step guide, easy to use templates and helpful tips. My employer won't give me a reason why I was terminated. You want to give at least a two weeks' notice. Sherral Schmidt, current president of the Police Officers Federation of Minneapolis, endorsed Kroll in a letter dated Dec. 24. St. Paul news -- including crime, politics, education, business, sports, entertainment and things to do -- from the Pioneer Press.