The easies way is to use WinSCP .NET assembly:
https://winscp.net/eng/docs/library

Or take a look at this example:
https://winscp.net/eng/docs/script_checking_file_existence

martin wrote:

You cannot rename file to name of an existing file.

So, is there a way that I delete previuos file if exists, and mv the file. I have to move the file via script else it stays there in original directory.

You cannot rename file to name of an existing file.

I am giving 'mv' command to transfer files. But if file already exists, it gives error. I want to overwrite file, if already exists. How to do this with 'mv' command?