Question

how to wright a letter to your principle that u r leaving the school ​

Answer 1

If it is a leave you are required to be able to take in your country then cite the piece of legislation and section relevant to the leave and rules as related to your time off.

If it is not a legally required leave, perhaps it is allowed under your company policy, in which case cite that.

If it is not protected at all, prepare, make a short case as to why you should be granted the leave that is succinct and does not provide too many personal details, and ties to how this leave will enable you to improve your performance upon your return.

As always in letters, look it over several times to make sure it is polite and courteous and will get you the response you are looking for, and that it is edited well.