Command are as follows:

For Sql Server 2005

BACKUP LOG
[DBNAME]
WITH TRUNCATE_ONLY
DBCC SHRINKFILE(
[DBNAME]
_log)


For Sql Server 2008



ALTER DATABASE [DBName]
SET RECOVERY SIMPLE;
GO
-- Shrink the truncated log file to 1 MB.
DBCC SHRINKFILE (DBName_log, 1);
GO
-- Reset the database recovery model.
ALTER DATABASE [DBName]
SET RECOVERY FULL;