How to remove a keychain in OS X?
I hate keychain issues...

In Finder use key-combo Command+Shift+G and paste in: ~/Library/Keychains/

Rename the CAC keychain file with .bkp extension at the end if you don't want to delete it. This should remove the file from your keychain.

If it is not gone in Keychain Access after that right click and delete it and select Delete References and Files.

The 'login' keychain is your default, if you want to reset it then go to the Keychain access preferences and select reset from there.

Then restart your Mac.