Milan Kaneria

This plugin will insert a link in the comment form that will allow the comment author to delete their personal info from it that is stored in a cookie. Only unregistered commenter will be provided with the delete link if they already had a previously posted comment.
Support
For support queries, please leave your comments on the plugin page.

ET Remove Comment Author Info

This plugin allows commenter to remove their comment author details from the comment form.

Newt Labs

This simple, lightweight plugin solves one particular issue. WordPress doesn’t include any alt text or a title tag when using Gravatars. This addresses that by using the comment author name for each of your comment’s Gravatars, and for any other Gravatar usage it should use the authors display name.
So if you create a post it will use your name for your Gravatars Alt text and Title tag and then for the comments it will use the commenters name for their Gravatars Alt text and Title tags.
With this plugin you can squash those pesky warnings given by SEO reporting tools that look for missing alt text and title tags.
<h3>Important Notes</h3>

Fix Gravatar Alt Text & Title Tag

Applies comment author name to Gravatar's Alt and Title tags in comments and author display name to Gravatars site-wide.

ET Remove Comment Author Info vs Fix Gravatar Alt Text & Title Tag