I wonder if your principal is confusing the school council and the PTO. School councils include administrators, teachers, and parents, and help make key decisions affecting the school. The school council is usually run by the principal, and the principal typically sets the agenda. School councils are required by (relatively recent) state law in many states. The PTO is a support group almost always run by parents, often with the principal and one or more teachers acting in advisory roles. I've heard of plenty of PTOs where the teachers hold offices, but I've never heard of a principal installing himself as president of the PTO. The principal has enough to worry about without trying to take on that role.