If you do not need to keep the transaction log then simply change the recovery model from FULL to SIMPLE. The transaction log will automatically truncate every few minutes as the database checkpoints and flushes the transactions from memory to disk.
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DBCC SHRINKFILE ( databasename_Log, 1)
dump transaction <YourDBName> with no_log
DBCC SHRINKFILE (<YourDBNameLogFileName>, shrinking size) --
-- then you can call to check that all went fine