Huratio is right. You'll find that UTS will look at your course average. However, if there is a low demand, and your reasons for dropping part of a combined degree are because you're not doing well in one (yet you ARE doing well in the other) you may find yourself lucky.
An example:
IT: 80
Business/IT: 85
Business:90
A student in bus/IT needs to prove themselves competent to move UP to business. From personal experience, a lot of the people in the double degree couldn't get into business, so they used the double degree as an "entry point", hence the need for a high credit average. However, the lack of demand for straight IT, combined with the fact that it is of a lower UAI requirement than the double degree means that UTS would probably have a lower requirement to drop business rather than to drop IT.
I can't say personally what you'll encounter, but more likely than not, you'd do best to at least try to pass the course you want to drop, and excel (as in, above average marks) in the course that you want to keep.