This article explains the steps to remove repo in Centos server.
Step1: Login to the server as root
Step2: Search the for the package name installed by executing this rpm command.
For example, if we are going to remove epel repository.
#rpm -qf /etc/yum.repos.d/epel.repo
Step3: Remove that package
#yum remove epel-release
Step4: Clear the metadata
#yum clean all
By this we can remove repository installed in Centos server.