How to complete remove filestream and all attached files

You can check:

SELECT * FROM SenONew.sys.data_spaces WHERE name = 'FileStream' 

it should return 0 rows.

There is a procedure to remove FILESTREAM features from a SQL Server 2008 database :

ALTER TABLE Filestore DROP column FileIndex
GO
ALTER TABLE Filestore SET (FILESTREAM_ON="NULL")
GO
ALTER Database SenONew REMOVE FILE fsSenONew
GO
ALTER Database SenONew REMOVE FILEGROUP [FileStream]
GO

as described in this article. But the steps you did should do the same thing.

Your problem is certainly strange, but I suggest that you try using following

USE SenONew
EXEC Sp_help 
EXEC Sp_helpfile 
EXEC Sp_helpfilegroup 

You may find something suspicious there like another table using that FILEGROUP.

I have done exactly the steps you describe and cannot reproduce your problem. Check how your Restore database screen looks like.

1.Remove the FILESTREAM attribute from columns and tables. You'll need to move data to a new column.

ALTER TABLE MyTable
ADD FileData varbinary(max) NULL;
GO
update MyTable
set FileData = FileStreamData
GO  
ALTER TABLE MyTable 
DROP column FileStreamData
GO
ALTER TABLE MyTable SET (FILESTREAM_ON="NULL")
GO
EXEC sp_RENAME 'MyTable.FileData', 'FileStreamData', 'COLUMN'
GO

2.Remove files from the FILESTREAM and drop the FILE and FILESTEAM.

ALTER DATABASE [MyDatabase] SET RECOVERY Simple 
GO

EXEC SP_FILESTREAM_FORCE_GARBAGE_COLLECTION 

ALTER DATABASE [MyDatabase] REMOVE FILE [MyFile]
GO
ALTER DATABASE [MyDatabase] REMOVE FILEGROUP [MyFileGroup]
GO

ALTER DATABASE [MyDatabase] SET RECOVERY FULL
GO