其实很简单，在安全邮箱发工单即可。工单内容的模版也提供给大家(可以看最后)。
首先先打开APP，选择更多。下划到个人资料和应用程序设置：
进入安全邮箱，点击下面的加号。
选择主题为服务请求-启动账户关闭流程。
Dear Sir/Madam:
I am writing to formally request the closure of my 360 account as I no longer require its use and wish to avoid any further maintenance fees. The account details are as follows:
Account Number: xxx-xxxxxx-xxx
Thank you for your prompt attention and assistance with this matter. Please let me know if any additional information is needed.
BR.