I disagree with the tense having to be the past - this cannot be obtained without more context. However the english translation definitely needs a particle prior to 'prince'. Unless they are talking about Pangeran (or artist formerly known as Prince) :D
To use the present tense you need more words - 'This school is closed by the order of the prince'. 'The school is now closed'.
As a standalone sentence, it is reflective of a decision the prince has already made and is being reported on. Therefore you have to use either past simple or present perfect.