Sometimes you need to delete any cached client SSL certificates from Safari. For instance, you may be testing different certificates with different levels of access on a site you are developing. Or, you may have selected the wrong certificate to logon a secured site like AKO or other DOD sites.
The problem with Safari is that it does not give you an obvious way to do this. However, it’s simple once you understand how they are stored.
To delete your client side SSL certificate, just open Keychain access and search for the website in question. You will see the URL under the Name column. Simply delete the entry and Safari will prompt you again for the certificate the next time you visit it.