Remove "Powered by..."

First of all let me just say that I am a "Newbie" so bare with me if I don't explain myself.....Ok, so here I go. Where do I remove the following code from. I am using the edu-clean theme. and can't find where it is.

Powered by WordPress MU and WP.MU
<script type="text/javascript" src="http://images.del.icio.us/static/js/playtagger.js"></script>Powered by WordPress MU and WP.MU