I already submitted my application to Middlebury College as regular decision. After more thought, I decided that I would rather do ED II. Is there any way that I can change this? (Both RD and ED II have a Jan 1 deadline)
Yes just email the admissions office and tell them, they will tell you if there is anything else you need to do.
Contact the admissions department of the college and ask if they will make the change. Let your.guidance counselor know as well.