Why did the school want to get rid of Mr Keating

Mr. Keating uses his unconventional ideas to negate the 4 pillars of Welton Academy and represents the progressive ideas that were rejected in the 1950's prep school. When Neal kills himself, largely because of his father's dominance in his life, Mr. Keating is fired. He is used as a scapegoat by the school to placate parents for Niel's death.