how to remove secondary transaction log file?

Try this

SELECT o.name AS TableOrIndex
 FROM sysfiles f
JOIN dbo.sysfilegroups s
 ON f.groupid = s.groupid
JOIN dbo.sysindexes i
 ON i.groupid = s.groupid
JOIN dbo.sysobjects o
 ON i.id = object_id(o.name)
 AND i.indid in (0, 1)
WHERE f.name = 'My_Logical_File_Name'
UNION
SELECT i.name
 FROM sysindexes i join sysfilegroups f ON i.groupid = f.groupid
 JOIN sysfiles l ON f.groupid = l.groupid
WHERE l.name = 'My_Logical_File_Name'

Use the DBCC SHRINKFILE with the EMPTYFILE argument command

dbcc ShrinkFile ('logical_file_name', EmptyFile)

You can also follow the below steps:

1. Connect to the instance of SQL Server Database Engine & expand the instance.
2. Expand Databases > right-click the database from which to delete the file, and then click Properties.
3. Select the Files page.
4. In the Database files grid, select the file to delete and then click Remove.
5.Click OK.