Whether you are itching to get rid of your Yahoo Mail account due to news that the service was hacked or due to other reasons, you should know that terminating your account is fairly easy.
If you're stumped on how to do so or can't seem to find the link to the option, this FAQ will show you the ropes.
N.B. Deleting your Yahoo Mail account will also block your access to all Yahoo services, including Flickr, contacts, and others.
Delete Your Yahoo Mail Account
First, sign in to your account. Then, head to Help > My Account > Register or delete account > Closing your Yahoo account > Account termination.
After you do this, you'll be prompted to re-enter your login details, which you should do.
You will then receive an account notification termination message. After reading it, you will need to confirm that you really want to delete your account by re-entering your password and filling out a CAPTCHA. Click Yes to delete the account.
N.B. Yahoo will keep your details on file for another 90 days. Do not use or try access your account for 90 days and it will be permanently deleted.