My brother is an alumnus of IET Lucknow and here is his input about the branch change policy. It entirely depends on a variety of criteria, including your first-year grades, seat availability, and, most significantly, your terms with the administrative wing.
I'd like to emphasize what I'm trying to communicate.
By the way, each college has its set of rules for branch changes, but the majority of colleges follow the methods outlined above when dealing with branch changes.