Leaving a job isn't easy. A short resignation letter is the way to go.Include your name, position, the date of resignation and the intended last day of work in the first paragraph. How to write a resignation letter that's effective immediately? Start with the facts and be direct. We've rounded up tips and examples for writing a resignation letter that'll help you maintain work relationships long after leaving a company. A one (1) week notice letter is written notification provided to an employer that an employee will no longer be working with the company within seven (7) days. Official Seal of the State of Arizona. Contact. Due to unforeseen circumstances, I must resign. (For example, "I regret to inform you that I will be resigning from my position, effective immediately.