Advanced Mac OS X Programming: The Big Nerd Ranch Guide

Editing the Keychain

With the item, you can also make changes using an attribute list:

OSStatus SecKeychainItemModifyContent (SecKeychainItemRef  itemRef,
                           const SecKeychainAttributeList *attrList, 
                                                   UInt32  newPasswordLength, 
                                               const void *newPassword)

The new attribute values would go into the attrList. A new password would go into newPassword.

To delete an item:

OSStatus SecKeychainItemDelete (SecKeychainItemRef itemRef)

Note that you would still have to call CFRelease() on the item to prevent a memory leak.