Hi,
Please go to Admin > Theme Options > Custom CSS/JS > Custom CSS – Find given below of code and remove, you should put this code at Admin > Theme Options > Custom CSS/JS > Custom JS. Now you can put the code as given my colleague David.
<!-- Facebook Pixel Code -->
<script>
!function(f,b,e,v,n,t,s){if(f.fbq)return;n=f.fbq=function(){n.callMethod?
n.callMethod.apply(n,arguments):n.queue.push(arguments)};if(!f._fbq)f._fbq=n;
n.push=n;n.loaded=!0;n.version='2.0';n.queue=[];t=b.createElement(e);t.async=!0;
t.src=v;s=b.getElementsByTagName(e)[0];s.parentNode.insertBefore(t,s)}(window,
document,'script','https://connect.facebook.net/en_US/fbevents.js');
fbq('init', '551909238321559');
fbq('track', "PageView");</script>
<noscript><img height="1" width="1" style="display:none"
src="https://www.facebook.com/tr?id=551909238321559&ev=PageView&noscript=1"
/></noscript>
<!-- End Facebook Pixel Code -->
Thanks
Mohammad