Simplenews adds newsletters title at the top of the newsletter
Find simplenews-newsletter-body.tpl.php in modules/simplenews/theme folder.
Copy it to your current theme's folder and open/edit it. You'll see that it has a $title variable printed at the top. Comment it out and clear cache to make Drupal see your template change. Test and see the title gone.

REMOVE OR COMMENT THIS LINE =&gt;  &lt;h2&gt;&lt;?php print $title; ?&gt;&lt;/h2&gt;
&lt;?php print render($build); ?&gt;