For NPM using SWQL the commands would be:
SELECT
CASE
WHEN AStat.AcknowledgedTime = '12/30/1899 8:00:00 AM' THEN ''
WHEN AStat.AcknowledgedTime != '12/30/1899 8:00:00 AM' THEN toString(AStat.AcknowledgedTime)
END AS [Acked Time]
FROM Orion.AlertStatus AS AStat
