How do I revert a change I made in the GECK back to it's original unmodified value? The change was saved to an esp, I know I can modify my change to be like original, but I would rather it not be present at all.

Maybe http://cs.elderscrolls.com/constwiki/index.php/Mod_Cleaning_Tutorial tutorial will help.

I have to go out in a few minutes, but at a quick glance that tutorial is exactly what I am looking for, thanks jackbarnard.