Removing Permanently Accepted Web Certificates in Firefox (Mac)
On a Macintosh
Start by opening the Firefox browser, click the Firefox menu, and then choose "preferences" on the drop down.
Click the "advanced" tab.
Click on the "Encryption" Tab.
Then click the "View Certificates" button.
Click on the "Servers" tab. Only those certificates listed as permanent under lifetime within the servers tab should be removed
*Caution is advised in deleting items that may be part of normal operations
Remove the certificate by clicking on it to highlight it, and then click the delete button.
Click "ok" before exiting.