It is possible to drop a course and register for another one

Hi so I realized that one of the courses I'm taking is too much of a hassle already - the professor is covering a material that I can't understand and the class is too early. Do you think I can easily drop it and substitute it for a new one? Do I need to get a professor's opinion to register for a new class. I'm aware that the last date to drop a course is Jan 16