I do not know how to uninstall FOP1 from Elastix GUI. In any case, you can create an apache alias to redirect /panel requests to /var/www/html/fop2 instead, so any link to /panel will open up FOP2.
http://www.fop2.com/docs/faq.php#HowtoreplacetheFOPlinkinFreePBXtoFOP2
