In SQL Server data is stored using two physical files:

1. (.mdf) extension which contains the data.
2. (.ldf) extension which contains log.

Log file size increases very rapidly and depend on the operation performed on the data. After a long time period this file becomes too large. When log file is too large it takes time to perform some operations like (attach, de-attach, backup, restore… etc ).

Step 1. Copy/type the below given SQL.

Step 2. Change @DBName to <Database Name>, @DBName_log to <Log File Name>

Step 3. Execute the SQL.

ALTER DATABASE @DBName SET RECOVERY SIMPLE WITH NO_WAIT
DBCC SHRINKFILE(@DBName_log, 1)
ALTER DATABASE @DBName SET RECOVERY FULL WITH NO_WAIT
GO