There's no way to remove part of file name using WinSCP operation mask.
You have to use some more powerful language.

E.g. you can use WinSCP .NET assembly PowerShell script:
https://winscp.net/eng/docs/library_powershell

Hi,
I am trying to rename the files while they are getting downloaded from the server to local directory, using operation mask i am able to replace the first two letters of the file with other letters
e.g get S_filename.CSV T:\Ruban\tt*.*
But my actual requirement is I have to remove the first two letters(S_) from the filename while the remaining letters have to be same. How to do this via commandline. please help