Dear Miss Zhang,
I appreciate the opportunity of working here for two years as an accountant, and particularly your constant assistance. It is with regret that I am writing to let you know that I will have to terminate my employment with your company as an accountant due to personal reasons.
Although this has been a difficult decision to make, I have been offered an opportunity that I believe will help me reach my long-term career goals. Therefore, I decide to quit this job and accept another one that better matches my ideal.
Thank you very much for the opportunity for growth that you have provided me. I wish you and the company all the best. I will try my best to assist in the hand-over process.