Issues with SEO how do I disable so can use SEO Yoast

At the moment same page titles etc are on each and every page - as the theme will not use SEO Yoast - which is not good practice.. please advise

Hi!
To get rid of meta discription that our theme provides you have to delete text (lines number 465-467) :

echo "<title>".sprintf($format,$title)."</title>\r\n";
echo '<meta name="Description" content="'.preg_replace('/[\'\"]/', '',$descr)."\" />\r\n";
echo '<meta name="Keywords" content="'.$keywords.$this->get( 'seo', 'keywords' )."\" />\r\n";

from folder inc--> library.php located in the directory of theme.