Allow users to delete their comments within editing time period
When a user (or guest) is editing their comment, they should be allowed to delete the comment as well.
Otherwise if someone makes a mistake and wants to remove their comment, they often end up just editing it and writing "Deleted" or something else which adds noise to the comments section.
See the implementation of Simple Comment Editing which allows this: https://en-ca.wordpress.org/plugins/simple-comment-editing/ It also comes with a nice editing window countdown which would be another good addition (but lower priority)
Users can delete own comments using the “My Content and Settings” button. it is located on the top left side of the main comment form.
Please read this document, here you will find more detailed information.