How to write a resignation letter that's effective immediately? Learn how to write an immediate resignation letter with our comprehensive guide, including tips, examples, and a customizable template.Just keep it short and sweet. Don't go into story telling mode. In the first sentence, clearly state your intention to resign and that your resignation is effective immediately. How to write a great letter of resignation that will let you leave gracefully. What was its immediate effect? A pair of scientific studies confirmed that lead contamination was present in the water supply.