How to write a resignation letter that's effective immediately? Explore why a good resignation letter is important and how to write it, and check out our free resignation letter examples.My resignation is effective immediately. This resignation letter sample provides your employer with a letter for your file and also suggests that you've done everything you can to remain professional. Use one of our resignation letter templates. (For example, "I regret to inform you that I will be resigning from my position, effective immediately. "I am writing today to inform you of my resignation as Project Manager at Logistics Company. I wish you both great success going forward. In the meantime, please let me know if I can assist you in any way during this transition period. Sincerely,.