Deferring your program (putting off starting it) is only for commencing students. It's not an option if you've already completed one or more semesters/terms of study. Find out more about deferment.
If you've completed one or more semesters/terms, and you need to take a break from your studies, you can apply for program leave. Program leave is available for up to one year, more in very exceptional circumstances. Find out more about program leave.