How can I delete Key Chain Certificates?

Upon an attempt to access an online site I frequent with Safari, MySubaru, this message box popped up:

Com.apple.Webkit. Networking wants to export "AppleID Authentication 2016-09-26 14:22:55 GMT -05:00 from your Keychain.

It asked for a password, I put in my mac password to no avail. After speaking with the Subaru tech support folks I was told this was an Apple issue and there was a way I could access my Key Chain and delete this.

I circumvented the issue by using Google Chrome. Still would like to figure out what all this meant.

Thanks so much.