I want to see actual precedence though, because the case you keep referencing doesn't really relate to you. I would imagine they are allowed to take down stuff that is put on their walls without permission.
the bylaws of the school do not forbid taping posters on the wall, and it does not matter if I myself was not involved in the court case I refer to. What matters is that in a court of law, a judge declared that the first amendment rights of students were protected in schools and unless the school can prove beyond a reasonable doubt that a student's expression is offensive to a reasonable person, then they cannot deny students their first amendment rights
If you read the OP, there are multitudes of other political posters made by students around the school and they have been there for months. There is no doubt in my mind that my poster was taken down because it featured Donald Annoying Orange, and not because it was offensive or distasteful, meaning the school is violating my first and fourteenth amendment rights.