Simply replace the unfilled areas such as "[]" and "[date]" with your information.
Dear [Employees],
It is with mixed emotions that I am announcing the retirement of [Employee First & Last Name]. [Employee First Name] has been with [Company] for over [number] years. [He/She] began working here as [entry position] in the [Department]. [Her/His] commitment and dedication to this company led [her/him] to become our [current position] within [Department]. [He/She] has played an important role in the growth and success of this organization.
[Employee First Name] has always been a diligent worker. Although we will miss him, he has more than earned the right to spend more time with his loved ones. Please join me as I extend our warmest wishes for the future to [Name] and his family.
Sincerely,