Archiving Files on FTP Server after get.

I'm sure this is somewhere and I just can't find it. I need to copy of group of files from an FTP server to my local computer. After I'm done, I want to move the files I've downloaded to an archive directory or maybe just delete them. Not sure yet. What is the script command to move files on the FTP server. Thank you for your time.

Use mv command:
https://winscp.net/eng/docs/scriptcommand_mv

I'm scripting using Powershell and use the $session.MoveFile() method for this purpose. If that is not the correct please let me know.

That's correct.
See https://winscp.net/eng/docs/scriptcommand_mv#net