SELECT     ServerName, 
               COUNT(ServerName) AS [Count], 
               Value, 
               Heading, 
               REPLACE(CAST(UTCOccurrenceDateTime as date),'-','/')
               --or try SELECT CONVERT(VARCHAR(10), UTCOccurrenceDateTime, 111)
               --or try SELECT CONVERT(DATE, UTCOccurrenceDateTime, 111)

FROM         Alerts
WHERE     (Heading LIKE 'Disk %') AND (Heading NOT LIKE 'Disk C%') AND (Value >= 95.00) 
AND DATEADD(hh, -6, UTCOccurrenceDateTime) >= DATEADD(day, DATEDIFF(day, 0, GETUTCDATE()), 0)
GROUP BY Heading, Value, ServerName, UTCOccurrenceDateTime
HAVING      (COUNT(ServerName) < 2500000)

SELECT CONVERT(VARCHAR(10), UTCOccurrenceDateTime, 111)
--or
SELECT CONVERT(DATE, UTCOccurrenceDateTime, 111)

SELECT
count(CONVERT(VARCHAR(10), UTCOccurrenceDateTime, 111)) as 'CountDate'
FROM         Alerts
WHERE     (Heading LIKE 'Disk %') AND (Heading NOT LIKE 'Disk C%') AND (Value >= 95.00) 
AND (UTCOccurrenceDateTime >= DATEADD(day, DATEDIFF(day, 0, GETUTCDATE()), 0))
GROUP BY Heading, Value, ServerName, UTCOccurrenceDateTime
HAVING      (COUNT(Heading) < 2500000)
ORDER BY UTCOccurrenceDateTime, ServerName