You probably don't need to remove your old version, but here's how you could go about it.
(these instructions would work for just about any software)
First you need to figure out where your current puppet is installed.
As root, run 'updatedb' to rescan you file system.
Let this chug a bit.
Then type 'locate puppet'.
This will show you all locations on your system with the word puppet in them.
Most likely, your puppet install is in
/etc/puppet/*
/usr/lib/ruby/1.X/puppet
/var/lib/puppet
and possibly
/var/puppet
The safest way to handle things is to mv these directories to another location.
ie 'mkdir /tmp/oldpuppet ; mv /var/puppet /tmp/oldpuppet/varpuppet' etc..
Also be sure to clean up the binaries. (most likely in /usr/sbin)
/usr/sbin/puppetca
/usr/sbin/puppetd
/usr/sbin/puppetmasterd
/usr/sbin/puppetqd
/usr/sbin/puppetrun
Puppet is a moving target with frequent updates. You may have no choice but to build puppet from source.
HOWEVER, you would be better suited to do RPM Builds of puppet. (thus creating .rpm packages that you can install on your redhat system, and get all the benefits of package management.)
Here's a document describing how to do just that.
http://agilesysadmin.net/building-puppet-rpms
Best of luck...