First backup your transaction logging:
- Tasks > Backup
- Select transactionlog backup en select a disk where to backup
- Now check the status with DBCC LOGINFO(DATABASENAME)
- Check if the last status record is 0 (zero)
- When the status is 2 make another backup
- When the status is 0 you can run: DBCC SHRINKFILE(2)
You can use this script also:
Backup LOG DBNAME
TO DISK = 'C:\SQL_TMP\transactionlog.trn'
WITH STATS
GO
DBCC LOGINFO(DBNAME)
DBCC SHRINKFILE(2)