Duzit,

How often do you backup your system?  If you dont you can run the code below to clean-up the LOG, HOWEVER please be aware that IF this is a production system then you may need to research backing up the database and log which will preserve your data.  (If this is still within your companies policy)

BACKUP LOG TestDB WITH NO_LOG

DBCC SHRINKFILE (TestDB_Log, 1000)

The 1st command issues a backup "DUMP" of completed transactions from your T-LOG and the 2nd will shrink the physical file down to 1GB or whatever size you tell it (IF you want). 

Good Luck