An account can be canceled by logging in and navigating to the Plan Info page. On the Plan Info page there is a link to cancel the account.
When an account is canceled, per our terms of service, all account data is deleted from our servers except for some aggregate usage data. After an account is canceled it will be scheduled for deletion. Once the account data has been deleted it cannot be recovered.
If you prefer to retain your Intervals data and temporary hold the account, there is an option to Park your account for a small monthly charge. Here are instructions on parking an account.