Forgot the password of a keychain (non the login one) I have installed a bunch of certificates on my mac, due to italian legal system, in order to login to a certain website with a smartcard.

It all worked well for a few months and then yesterday it started to ask me the password for a keychain called SmartcardS00...and a bounce of letters.
When I open the app keychain and I look into this locked keychain it shows me the certificates and in order to do something I need the password it asks me, but I don't know if I have ever know this pwd or not.

I tried to " delete " the keychain and try to reinstall all the certificates from the thumb drive with the smartcard, but I can't find the option to delete it anywhere.

PS I have MacOs X 10.11.1

Hope you understand my english.
You can reset your login keychain by opening Keychain Access from /Applications/Utilities and in Preferences selecting Reset My Default Keychain. Be aware of the statement shown beside the reset button.