Write a letter seeking clarification regarding your retirment
Kindly accept this as formal notice of my retirement due on (date of retirement). I would like to inform you that I will be leaving my position of (your job title and department) from that date.
I would like to thank you for your support during my time with the company, which I have found enjoyable and fulfilling. Kindly let me know the arrangements for handing back equipment, company car, etc, and handing over the work and other responsibilities.