求问如何写邮件礼貌拒绝已经接受的offer

之前接受并交了一个项目的留位费来保底，交完也没继续办其他手续。现在拿到了更想去项目的offer，决定放弃之前那个，我知道该给之前的学校发个邮件说明一下。不是很清楚应该怎么写这个邮件，标题、内容应该写什么才合适得体？求解答

Subject: Application Status Update

Dear Sir / Madam,

Thanks for the offer. It has been a while since I was admitted to the program. A lot of things happened and I need new plans for myself due to new situation. Therefore, I am afraid I will have to decline the offer. Sorry for any inconvenience and thanks again for your consideration.

Best Regards,
<Your name>