How to un-install mods?

So I've seen alot written about how to get mods installed, but how does one Un-install a mod? I'm assuming there is more to it than simply deleting the .exe installer in the install folder. I am also assuming that for the mod to completely uninstall you have to start a new game (I got used to this idea thanks to the Bethesda modding community with Skyrim / Fallout).

That said, can someone point me to an article or video which covers this? I know there has to be one floating about.

Thank you for any help you may be able to point my way.