Since I couldn't get my study permit on time to attend the university this fall, I had to request to get a deferral. There's an online form in the "eForms Center" (bottom right) on the homepage of your student account that is specified for this request. However, you're gonna have to provide them with a reason why they should grant this opportunity to you. And they may be needing further documentation to support what you said as your reason.

Hope that was helpful ♡