http://confluence.atlassian.com/display/DOC/Editing+the+Footer - explains how to modify the property files inside of a jar file.
Instead, I just keep it simple, edit ./confluence/decorators/includes/footer-content.vm and comment the first instance of,
$action.getText('licensefooter.community',[$action.getText('url.atlassian'), $action.getText('hitcounter.community'), $license.organisation])<br>
using #* text *#
#*$action.getText('licensefooter.community',[$action.getText('url.atlassian'), $action.getText('hitcounter.community'), $license.organisation])*#<br>
Just refresh your browser to see the change take effect.
I also found that commenting out the following gives more space,
<!--ul id="poweredby">
<li class="noprint">$action.getText('powered.by.atlassian.confluence',
[$action.getText('url.atlassian.software.confluence.footer'),
"<span id='footer-build-information'>$generalUtil.versionNumber</span>",
$action.getText('url.enterprise.wiki.footer') ])</li>
<li class="print-only">$action.getText('printed.by.atlassian.confluence',["$generalUtil.versionNumber"])</li>
<li class="noprint"><a href="$action.getText('url.bug.feature.request')" class="hover-footer-link">$action.getText('bug.feature.request')</a></li>
<li class="noprint"><a href="$action.getText('url.footer.atlassian.news')" class="hover-footer-link">$action.getText('footer.atlassian.news')</a></li>
</ul-->