That's all there is to this entire discussion. I'm amazed at so many points of view. You pay the deposit. You decide not to attend (for any reason whatsoever--maybe you decide you don't like the school colors). You simply call or e-mail, "I will not be attending," no explanation required. You forfeit the deposit. Everyone moves on. There is no moral issue here at all. None. Absolutely nothing different than putting a deposit on an apartment you decide not to rent.