I am using Firefox. For untrusted certificates, one may choose to accept. I want to know where to view those certificates and then how to clear them. I try clean the cache, but after that when I reload the same page (via HTTPS) it does not ask me to accept certificate. So it still remains in the browser somewhere.
In Firefox 20 or higher, you can look in Tools → Options → Advanced → Certificates → View Certificates, which lists all certificates used in Firefox. You can then delete the ones you want to remove.