According to Reb Moshe Feinstein, zt”l once a child has been admitted to a yeshiva/bais yaakov, you are not allowed to throw that child out for not paying tuition.
It is also very troubling that a mossad or girls school even if they are private institutions to throw a child out. First, that child is prone to go off the derech, which would be the yeshivas fault
But more important, is that these institutions are not private once they accept donations/charity etc. All of these schools solicit funds from the general public and therefore, have to adhere to a philosophy they they are public institutions and act accordingly, MEANING it is forbidden to throw a yiddisha neshama to the streets because the parents cannot afford the tuition