How can i cancel a yahoo email account that belongs to me?

You can ignore your account for at least 4 months and it will automatically be deleted for inactivity, or you can go about deleting it yourself. When you terminate your account, you permanently lose all saved data and Yahoo site access associated with your ID. You’ll be deleting your email account, address book, group memberships, Y!Answers account, Y!Messenger ID, any photos you’ve uploaded, any 360 blogs you’ve posted, etc. If you're sure you want to delete your account, click on this link: https://edit.yahoo.com/config/delete_user Yahoo will ask you to enter your password one last time and then you will click on the "Yes, terminate this account" button. Your entire account will then be completely & irretrievably deleted.

Actually, the easiest way to close your free Yahoo account is to do nothing. By not using your account (that means not even logging in to check it) for 4 months, Yahoo will automatically deactivate it and erase all content. Here is the help link that explains what happens if you close your Yahoo ID... http://help.yahoo.com/l/us/yahoo/mail/yahoomail/account/account-11.html

just don't use it and after a month or so it will be automatically cancelled

Go to https://edit.yahoo.com/config/delete_user and follow the steps to close out your account.

use this Yahoo deactivate link just sign in too the Account you want to Delete and put in your password as required then fill out all the required stuff in the deactivate page https://edit.yahoo.com/config/delete_user this will fully Delete your Account.