Read This, it may be helpful.
You could always try using spotlight to find the codecs and then putting them in the trash.
As always, be very careful about what you download and from where. Those codecs were downloaded from somewhere that is not altogether trustworthy.
P
How can I get rid of these codecs? Using Leopard on a G5 Mac. Thanks

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic