How can i remove duplicate encoding meta tag
If the &lt;meta charset="utf-8"&gt; tag is appearing twice in the rendered HTML, chances are one of the instances is hard-coded in your theme's html.tpl.php template, while the other is inserted by the metatag module.

I'd recommend checking your theme templates. In some cases, freelancers with little Drupal knowledge may create several page level templates duplicating the head, header, and footer markup too.

As Alfred noted in his comment, removing this tag should be done server side and not via javascript.  While it does add a few bytes to download of the page, it does not critically effect search engines from detecting the page's content for indexing.