"As a parent who recently withdrew a child from one of our classrooms, we want to ensure that we gain an understanding of your decision and do what we can to improve our operations."
"We" cannot be "a parent." Thou shalt beware of "As" at the beginning of a sentence.
Thou shalt also not be wordy by saying "gain an understanding of"; just "understand" will do.
Let's reword the entire monstrosity:
"We would like to understand why you recently withdrew your child from one of our classrooms. Please fill out this survey and help us improve our operations."