To remove a secondary sql transaction log file is accomplished by the ALTER DATABASE REMOVE FILE command .   You may have needed to add a second transaction log file to deal with a very large transaction . Now the transaction is finished , you’re looking to delete the secondary transaction log file.

USE [mydatabase]
GO
ALTER DATABASE [mydatabase]  REMOVE FILE [mydatabase_Log_2]
GO

But under certain circumstances this error message may appear

Msg 5042, Level 16, State 1, Line 1

The file 'mydatabase_Log_2' cannot be removed because it is not empty.

To fix this error use the DBCC SHRINKFILE with the EMPTYFILE argument command

dbcc ShrinkFile (mydatabase_Log_2, EmptyFile)

The EMPTYFILE argument moves data from the chosen file to another file in the same filegroup.Once completed , rerun the ALTER DATABASE  command

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