Cannot Delete Key from System Keychain
I am having a bit of a problem deleting keys (any keys) from the System keychain on my iMac. Here's what happens:
- I go to Keychain Access and select System from the list of keychains.
- I unlock the keychain using my admin password (the icon changes from locked to unlocked).
- I left-click on the key that I want to delete and select Delete "The Key I want to delete"
- I get a box that says "Keychain Access is trying to modify the system keychain, Type your password to allow this." So I do.
- I get a box that says "Are you sure you want to delete "The Key I want to delete" from the System keychain?" I click 'Delete'
- I get a box that says "An error occurred while deleting "The Key I want to delete" UNIX[Operation not permitted]
I am not able to change any of the information in any of the System keys nor am I able to add new keys to the System keychain. My System keychain contains 20 items - all of which are either passwords to WiFis, passwords to Time Machines (which I want to delete), and one application password to the guest account. This being said, I would have no problem "resetting" the System keychain to default (empty) condition.
I also have a MacBook, which is not exhibiting this problem. That is to say that I can freely edit, delete and create keys in the System keychain. I followed the instructions here to backup the system keychain from my MacBook and install it on the iMac, but get an error saying "Operation not permitted".
Any ideas?
Thanks!
iMac (27-inch Mid 2010), OS X El Capitan (10.11.1)