You may be using a Web browser that does not support standards for accessibility and user interaction. Find out why you should upgrade your browser for a better experience of this and other standards-based sites...
Open the Kerberos application (usually found in the Applications->Utilities folder), highlight the name of the Kerberos "ticket," then click on the Destroy button. Then quit Kerberos.
You can now walk away from the computer knowing that the next person to use it can't impersonate you by using your open Kerberos ticket.
