Comment author email address is required so you cannot eliminate it but you can “force” it to be a particular value and hide the field on the comment form.
Copy comments-form-tpl.php to my-comments-form-tpl.php file. In the new file change:
<input class='tb-field' type='text' name='form_email' value =\"{$_REQUEST['form_email']}\" maxlength='70' /> <label class='tb-required'>*</label> <label class='tb-label'>{$lang['comform4']}</label>";</code>
<input type='hidden' name='form_email' value ='nobody@nowhere.com' />In admin panels > maintenance menu > edit configuration settings: