Add the following script tage in your knowledgebase settings https://kb.help.usepylon.com/articles/6944132996-how-to-add-custom-css-to-your-knowledge-base
<script>
// remove powered by link.
(function(){function r(){var e=document.querySelector('a[href="https://www.usepylon.com/"]');e&&e.remove()} new MutationObserver(r).observe(document.documentElement,{childList:!0,subtree:!0}); setInterval(r,2000)})();
// Add other modifications below