Dear Khun Perasit,
I regret to inform you that, I would like to resigning from my position as Purchasing for the What is green Company. My last day of employment will be June 30, 2015.
Thank you for the support and the opportunities that you have provided me. I have enjoyed my tenure with the company.
If I can be of any assistance during this transition, please let me know. I would be glad to help however I can.