Dear Sir or Madam,
Please accept this letter as formal notice of my resignation from my position as [job title] at [company].
Thank you for the support and the opportunities I have had during my time here. I have learned a great deal and have enjoyed working with the team.
I will do everything I can to make the handover smooth, including documenting my work and helping to train my replacement.
I wish you and the company every success.
Yours sincerely,
[Your name]