How to write a resignation letter that's effective immediately? Learn how to write a professional resignation acceptance letter with our helpful guide.Below is a sample union resignation letter. You should check your union's constitution and bylaws to see if it is specific to whom a resignation must be sent. Explore why a good resignation letter is important and how to write it, and check out our free resignation letter examples. Learn how to write a professional resignation letter with our stepbystep guide including 15 resignation letter examples for various situations. Sample resignation letter format with immediate effect. Resignation acceptance letter with immediate effect word format. The following are examples of letters from a manager accepting an employee's resignation. Use these examples to help you write your own letter.