Remove yum repo using yum

In order to remove the actual yum repository rather than just to disable it, you have to find the package and remove it.

rpm -qa | grep epel

Sample outputs:

epel-release-5-4

yum remove epel-release-5-4
yum clean all

you can remove the repo with yum-config-manager but not with yum:

yum-config-manager --disable repository
yum-config-manager --add-repo http://www.example.com/example.repo

EDIT: you need some way of running this as root (ie. sudo)

You may be able to go into /etc/yum.repos.d/ and remove the file corresponding to the repository.