Configuration/settings/do not sync from ldap
$c->do_not_sync_from_ldap = array( 'admin' => true );
A list of usernames that should not be synced from LDAP. For use with the LDAP driver only.
Note this setting does not mean that LDAP authentication is not attempted for the named user(s), it simply means that when the list of users is synced from LDAP and any of these users are unknown to LDAP, they will not be deleted from DAViCal. If users not known to LDAP should be able to log on, you will probably want to set
$c->authenticate_hook['optional'] = true;