Learn how to write a resignation letter with a notice period. Dear Sirs: Effective immediately, I am not a member of UFCW Local 99.State your resignation and provide the effective date. 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. Start with a two weeks notice letter. This will serve as a formal, written documentation of your intent to leave and your transition timeline. Example 1; Example 2; 4. Concluding Your Resignation Letter: FAQs; Can I resign effective immediately?