This function clears the DHIS2 credentials from memory. If an auth object is
provided, it clears the credentials from that object. If no auth
object is
provided, it clears the global auth credentials.
See also
Other credential functions:
khis_base_url()
,
khis_cred()
,
khis_display_name()
,
khis_has_cred()
,
khis_username()