If you've ever followed the instructions in one of these hints to add an X509 anchor ... and later regretted the fact, you might have looked for a way to delete the certificate. If, like me, you searched in vain for a way to do so, this hint is for you.
It's really quite simple. In Keychain Access (in /Applications: Utilities), select "Add Keychain� from the File menu. Maneuver your way to /System/Library/Keychains, and add X509Anchors. (You shouldn't need X509Certificates.) Once you've added the keychain, it'll appear in the drawer. Select it, and you can view any of the certificates. You can manage these certificates the same way you would those on any other keychain. Specifically, to delete a certificate, just click on it and hit the Delete button. Keychain Access will probably ask you for your own password.
Note that there's no need to unlock the keychain, as it's stored unencrypted on disk. Indeed, if you attempt to unlock it, you won't be able to supply a valid password. Presumably, Apple should recognize unencrypted keychains and disable the Unlock button for them.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050127174234136