kdestroy destroys the user's active
tickets by writing zeros to the specified
credentials cache that contains them.
If the credentials cache is not
specified, kdestroy destroys the default credentials cache
(/tmp/krb5cc_UID where UID is the
decimal user ID).
specify the credentials cache pathname.
The format of cache is FILE:filename.
alternate default cache
default credentials cache
Only the tickets in the user's current ticket file are destroyed.