Welcome to L.Q.
In RedHat Based systems you have the RPM (RPM Package Manager) that lets you manage the packages you have installed.
Open up a terminal and type : rpm -qa
This should give you a list of rpm packages you have installed.
If want to see if any particular package is installed on you system type : rpm -qa | grep <package name>
On any system packages can be installed/uninstalled in many ways :
1) Packages can be installed by source.
2) Packages can be installed by an installer file (.run, .bin, .sh)
3) Packages can be installed using the native package manager for the distro (which in case of RedHat is RPM)
In the first two cases package management may not be that easy if you are not used to it. For removing the package you would have to remove all the files manually.
For the third case however the distro provides the package management tool.
If you want to remove any rpm package, open up a terminal and as root type :
koodoo@knapsacker:~$ rpm -e <package name without the .rpm extension>
Type man rpm to learn about RPM, also google the same.
Post what package you wish to uninstall. Be more specific i.e. how did you install it (i.e. from source, from rpm, etc)
Hope this helps.