SELECT CONVERT(varchar, StartTime, 100) AS ST,
CONVERT(varchar, EndTime, 100) AS ET
FROM some_table
or
SELECT RIGHT('0'+ LTRIM(RIGHT(CONVERT(varchar, StartTime, 100),8)),8) AS ST,
RIGHT('0'+ LTRIM(RIGHT(CONVERT(varchar, EndTime, 100),8)),8) AS ET
FROM some_table