The principal WOULDN'T want to kick out students before they graduated, or the school would lose the funding and would have dropout rates increased.
So, either you don't know the reason certain students are being kicked out because you don't have all the information, or this principal is choosing to throw away money and reputation. I'm going to bet on the first reason.
Who are you in this fight? A parent or a student? Because I'm praying you aren't the teacher, Maestro, because your spelling and grammar are atrocious.