You can't change your exam centre after submitting the application form of jee mains.But if the exam centre of first choice that you had filled then jee will allot you the exam centre of other two city choices.
For more details you can contact jee through email or telephone numbers.
All the best:)

Could you please clarify the question once,if you are asking about change of test center of jee mains after the form fillup,then my ans wud be No u can not.btw plz specify the exam name and clarify the question.