You can assign and un-assign sections for a class in an academic year. Yes, you can have sections specific to the branch. Please note the following
1. Sections in which students are available, cannot be unassigned for the academic year.
2. Sections cannot be assigned to the branches which are created as a non-revenue branch.
3. Classes which are of coaching/training can be given start and end date for each section.
Path: Settings / Organisation/ Assign Sections