Recently I was discussing about removing transaction log files on the #sqlhelp hashtag on Twitter. The question was whether we could remove an existing transaction log file after adding a new one. During the course of the discussion, I learnt that the file that was being removed was the primary transaction log file of the database.
When you attempt to remove the primary log file of a database from Management Studio or using ALTER DATABASE command, you will receive the following error:
Drop failed for LogFile ‘dbLogTest_log’. (Microsoft.SqlServer.Smo)
The primary data or log file cannot be removed from a database. (Microsoft SQL Server, Error: 5020)
This is by-design. We do not allow the removal of the primary transaction log file of user databases. This was first introduced in SQL Server 2000.
Tibor (Blog), a SQL Server MVP, has already blogged about how to remove transaction log files using T-SQL commands here. So, I am not going to duplicate the post here again by providing the same T-SQL commands.
TroubleshootingSQL 
How to identify primary log file?
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Execute the query below under the context of the database that you are interested in finding the log file information for. The file with the lowest file_id value is the primary log file.
use
select * from sys.database_files
where type_desc = ‘LOG’
order by file_id
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