Filing Requirements. Learn how to write a professional resignation letter with our step-by-step guide, easy to use templates and helpful tips.It is not legally required. We've rounded up tips and examples for writing a resignation letter that'll help you maintain work relationships long after leaving a company. Before resigning as a member in good standing, an attorney must satisfy any outstanding membership obligations. "A resignation letter should be short and to the point. Simply explain why you're leaving and the date of your departure. 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. "Learn the essential steps and tips for writing a professional two weeks notice resignation letter.