How do I hide a GTM code on my header and footer.

My advertising agent sent me a GTM code to insert onto my website in the header and footer. I had a similar code with a previous agent. When I replaced the code that was there, with the new one provided, it suddenly became visible to the public (particularily on the mobile version). This obviously looks terrible. Can someone help me figure out how to hide this?

www.maverickpestsolutions.ca

Here is my website so you can see what I mean.

Here is a Screenshot of the code showing up under my header. I am going to delete the code until I can find a solution as it looks terrible as is.

Wrap the code with script tag

<script>

the code here

</script>