you can disable the epel repo with the --disablerepo=epel
what did you install from epel ?
if you uninstall the repo without first uninstalling the rpm's you installed from epel you will have problems !
also is "yum-priorities-plugin" installed ?
it REALLY is NEEDED if you install third party software repos
see the centos wiki page
and the page for the plugin
also please post this ?unknown? "script" you are trying to run