Making a retirement letter which is addressed for your employer or the office you are working on is easy. First, of course you have to mention the contact information of the employer first. Then you can start with Dear Mr. or Ms. Who (your employer). You mention in the first paragraph about the aim of the letter, that is your retirement. In the second paragraph, you can write about your thanks for the employer and all the staff for letting you in the company. You can say that you are very grateful to have worked in the company.
I am happy to announce that I will have my retirement from your company effectively start from March 1, 2017.
There are many things I have got from my experience working here until this time I finally have to retire permanently from this company. I am very grateful I have ever been a part of this great business. Now I am going to retire and I will miss every time I work in this company. I thank all the management and the staffs for the guidance and acceptance in this company. These meant so much for me.
Because I retire, there must be an empty chair in your company now. I am ready if you ask me to fill in or to train the new employee, so can be sure about the quality that we have. Thank you for letting me becomes the part of this company.
Below is the template with retirement word samples you can download and modify to suit your needs.