If you no longer use your Yahoo email address, or you know that your account has been hacked and someone else is also using your account, you may want to delete the account. Yahoo will allow you to delete your Yahoo user ID, but deleting your account will remove you from all Yahoo services, including Messenger, Fantasy Sports and Yahoo Games.
Go to the Yahoo! account deletion (See Resources). If you're not already logged into your Yahoo! account, you will be prompted to do so.
Read the page and be sure you understand the terms of service, including what information of yours Yahoo might retain. Be sure you have deactivated any Yahoo! premium services that may require a fee.
Enter the password for your account to confirm that you wish to delete your Yahoo ID.
Complete the visual confirmation code. This, along with your password, will confirm you actually want to delete your ID.
Click "Terminate this Account" at the bottom of the account deletion page. Once clicked, your email and ID will be deleted from the Yahoo system and cannot be recovered.
Back up any important email or documents saved in your Yahoo email account before you lose the account.