The /upload (and similar) command-line parameters are not intended for automation.
For automation, use scripting:
https://winscp.net/eng/docs/guide_automation

I created a stored session I can use from a Windows .bat to upload a named file to a remote server: WinSCP.exe <session_name> /upload <filename>.

I also have a stored session for downloading which I can use from the GUI. I need to have a download .bat also, to download and delete all files from a remote folder. I cannot figure out the Command structure to do this as there is no /download command. Can someone help please?