How to fully undo adding repositories to Centos?

I'm using CentOS release 6.2 (Final) at work, and wanted to upgrade Firefox from 3.6.24 to current version. Reading some online manual, I did the following:

wget http://ift.tt/10mIRza
sudo rpm -Uvh epel-release-6-8.noarch.rpm
wget http://ift.tt/1fY6w3I
sudo rpm -Uvh remi-release-6.rpm
rm *.rpm
yum --enablerepo=remi list firefox
sudo yum --enablerepo=remi install firefox

But, when I saw how many packages it's going to upgrade (on a production machine!), I got frightened by such an intrusive "firefox upgrade" and cancelled the installation. I decided to roll back addition of the repositories. Namely, I did

rpm -qa | grep -i remi
rpm -qa | grep -i epel

and deleted the packages which these commands listed:

sudo rpm -e remi-release-6.5-1.el6.remi
sudo rpm -e epel-release-6-8

But it didn't actually appear to change anything: sudo yum install firefox still wants to upgrade that ton of packages. So, it seems I've not rolled it back.

How do I undo all this mess?