Easy with Simple Recovery
DBCC SHRINKFILE ("<FileName>_Log", 1); GO
otherwise
USE AdventureWorks2008R2; GO -- Truncate the log by changing the database recovery model to SIMPLE. ALTER DATABASE AdventureWorks2008R2 SET RECOVERY SIMPLE; GO -- Shrink the truncated log file to 1 MB. DBCC SHRINKFILE (AdventureWorks2008R2_Log, 1); GO -- Reset the database recovery model. ALTER DATABASE AdventureWorks2008R2 SET RECOVERY FULL; GO