* Go to Mail.Yahoo.com and log into your account.
* Look for the "Help" link, which is in the top right of the screen under the search box.
* Choose the "Account Configuration" link under the "Using My Yahoo! Mail Account" section of the main Help page.
* At the bottom of the page, you'll see a section called "Closing My Account". Choose the "How do I close my account?" link.
* Follow the instructions on the screen to close your Yahoo account.
NOTE: Even though your account will be instantly marked as being cancelled, it will actually be removed about 90 days later.