if you'd like to remove "Register" link in Banner portlet, you can do so at this file:
And I think that you'll also want to remove page and node definition for "Register" page at
server/$CONFIG/deploy/gatein.ear/02portal.war/WEB-INF/conf/portal/portal/classic/navigation.xml and pages.xml
Good luck and have a nice day.
Regards, Michal Vančo, JBoss QA