Hey Eric,
Sorry for my vague explanation.
Log in the backend of joomla.
Go to components-> compojoomComment -> settings. Then click on the content settings and go to the layout tab.
Select yes for this option: "Copy current standard template to customized template directory:" click apply.
After that go again to the layout tab and from "Your customized template:" option select the new template there.
After that click on the "Modify current customized template:" yes. Click again on apply and now you should see 2 new tabs - html and css. Go the html tab and find:
{poweredby}
<!-- powered by will be inserted here.
to hide, please do not delete. Just set in css #poweredby { display:none; }
-->
{/poweredby}
delete the above code and you are ready to go.
Daniel