I write this letter to formally say goodbye to you as I resign from my post as assistant sales manager in the company. Under your supervision, I have grown personally and professionally in the past fifteen years. I am proud to have known you and worked with you as sales manager. If not for your advices, I would not have reached my position and worked well until my resignation. You have also made my last years in the company very meaningful.
Thank you for being a mentor and friend. I would not have survived the many struggles I faced in the profession without your support. I wish you all the best in your career. May your career continue to flourish and prosper in your life.