How to remove your Yahoo account
Direct link to delete your account, and of course, all associated Yahoo services cannot be used anymore. So also Flickr (if you have it) will be removed by this action! If you wish to delete only your Flickr account, find Flickr in our list: you can delete that one separately.
Direct removal link: https://edit.yahoo.com/config/delete_user
Helpful Trick: Removing online data