Sir,
I am writing to inform you that I will be resigning from [Company Name] from the position [Position]. My last day of work will be [Date].
I would like to thank you for having me as part of this organization. I am proud to have worked for [Company Name], and I appreciate the time and support which you have given me throughout this tenure. I have learned a lot, mainly in the [eg. new web technologies] and these skills will serve me well in my career.
Please acknowledge this letter as my official notice of resignation. I will do my best to ensure that all of my projects are completed and ensure a smooth transition. I have been fortunate to have been a part of [Company Name] and I wish you continued success.
Sincerely,
[Your Name]