DECLARE @EndDate DateTIme 
--Set to save 1 year of data
SET @EndDate = dateadd(year, -2, getdate())

deleteMore:
DELETE TOP(1000) FROM CompressedDeviceEvents WHERE StartTimeStampUtc < @EndDate;
IF @@ROWCOUNT != 0 goto deleteMore

deleteMore2:
DELETE TOP(1000) FROM DeviceComponentStateDay WHERE StartofDayUTC < @EndDate;
IF @@ROWCOUNT != 0 goto deleteMore2

Truncate table DeviceEventBlob;

DBCC ShrinkDatabase( 'EnterprisePowerManagementDB', 0);