Can I study theatre management as its own separate discipline, as a separate “major” in college?
Normally not as an undergraduate. Practically all “self-standing” theatre management programs in the U.S. and Canada exist only at the graduate level. As an undergraduate, you need to learn some basic skills such as scheduling, accounting, publicity, audience development, human resources and the like; and also gain an understanding of what this broad field involves. Then you can can focus your particular interests at the graduate level.