Basic Resignation Letter Sample. How to write a resignation letter that's effective immediately?Use one of our resignation letter templates. Start with a two weeks notice letter. This will serve as a formal, written documentation of your intent to leave and your transition timeline. Your resignation letter should be brief and to the point. You don't need to include lengthy explanations about why you are resigning. In this article, we cover everything you need to know about writing a resignation letter without notice and provide an example to get you started. (For example, "I regret to inform you that I will be resigning from my position, effective immediately. Having delivered my resignation.