Answer
Deleting a Yahoo Mail account means not only that your emails will be removed and you’ll lose access to your account, but you’ll also no longer have access to your My Yahoo settings, your Flickr account and photos, and other data stored in Yahoo’s services.
How to Delete Yahoo Account Permanently
How to Delete Your Yahoo! Email Account
What happens if I delete yahoo account?Deleting a Yahoo Mail account means not only that your emails will be removed and you’ll lose access to your account, but you’ll also no longer have access to your My Yahoo settings, your Flickr account and photos, and other data stored in Yahoo’s services.