Top Law Schools

I just got off the waitlist at a school i wanted to go to since the beginning, and so i put down their deposit. now i have to withdraw to the school i first committed to, and i'm not sure how i do that. do i just shoot the dean of admissions an email saying "sorry but i got off a waitlist and will be attending there instead, i'd like to have my application withdrawn"? i know that's what you say when you withdraw from a school that's still considering you, but what's the proper wording when withdrawing to a school you committed to?

i know this is really tedious but the dean of admissions at the original school has been great all throughout the process and i want to do this right...

What I did was send the appropriate person an email informing them of my intention to withdraw and that a letter would soon be arriving in the mail. The deposit sheet of the school had an address on it letting me know where to send a letter of withdrawal and who to make it out to.

My letter basically said that school A is a great school which I would have loved to attend but ultimately I have decided on school B after much thought. I then thanked school A for the offer and that's about it. It's not that hard : ).