If you're thinking about closing your account, just head over to the parent account (you can check out this article for details on Account Hierarchies). Go to Settings > Account, and click on the General tab. You'll find the Close my account button at the bottom of the page.
Alternatively, you can submit a request with your name, account number and the reason for cancellation.
| Note - if you only want to disable a sub-account, see this article for instructions. |
Follow the prompts/ questions about why you wish to cancel and then submit your request: