Dear …
RE: Withdrawal of Application for __(Name of School/Course)__
I want to thank you for the time you have taken to review my application for enrollment in __(Name of School/course/etc.)__. It is with regret, however, that I must inform you I am withdrawing my application at this time, due to a change in the focus of my __(major/graduate study/etc.)__.
After much consultation and consideration, I have decided that a __(type of)__ __(major/degree/etc.)__ is the better path for me to take. This, of course, has __(led/forced/etc.)__me to __(consider/apply to/enroll in/etc.)__ other __(schools/courses/etc.)__. I do feel quite strongly that I have now made the right academic choice for my future and I genuinely apologize for any inconvenience this decision may have caused your department.
Thank you for your patience and tolerance in this matter.
Sincerely yours,