How are cached usernames and passwords cleared from the memory of a R76 Security Gateway?

How are cached usernames and passwords cleared from the memory of a R76 Security Gateway?

A.
By using the Clear User Cache button in Smart Dashboard

B.
By retrieving LDAP user information using the command fwfetch dap

C.
Usernames and passwords only clear from memory after they time out

D.
By installing a Security Policy