Hi aspirant,
You have not mentioned in which College you want to cancel admission. It is important to know College name because admission cancel procedure varies from College to College. In some Colleges admission fees will not be refunded but in some  Colleges they'll refund the admission fees and Terms and Conditions are applied for it. There will be deadline in some Colleges to cancel the admission.
So, without knowing the College name and details it is difficult to answer your question. Kindly comment or re-post with the information required for answering your question.
May this information was helpful to you.
Good Luck!!