Dear Mr./Ms. Last Name:
I would like to inform you that I am resigning from my position as XXX for the XXX, effective Dec 15th.
Thank you for the opportunities for professional and personal development that you have provided me during the last N years. I have enjoyed working for the xxx and appreciate the support provided me during my tenure with the company.
If I can be of any help during this transition, please let me know.
Sincerely,
Your name
