Congratulations on your offers! Generally speaking, accepting an offer and enrolling in a degree are separate actions that lead to two different statuses. When you accept an offer for a degree, you are essentially at a stage where you have the ability to enrol in that degree. However, this does not mean that you are forced to enrol in the degree. Whether you choose to enrol depends on whether you wish to study that particular degree at the university from which you received the offer. If you decide not to enrol in a particular degree, there would be no need to withdraw.
On the other hand, enrolling in the degree means that you are officially a student studying that degree at the university from which you received the offer. As such, you will be subject to university fees and HECS debt following relevant census dates. From this point, you can complete the degree, or unenrol at any point in time if you wish to transfer to an equivalent degree at a different university, or if you find that you wish to change your field of study completely.
In your case, it would be good to accept your offers so that you have backup options in the event that you end up not receiving an unconditional offer from UNSW.
I hope this helps!
