So are you using scripting or do you just start the GUI "keep remote directory up to date" feature from command-line? I suppose the latter. In that case you need to enable the Delete option here:
https://winscp.net/eng/docs/ui_keepuptodate

For synchronize client and server I use /keepuptodate with a script.
Perfect but when I delete file from client winscp don't delete file from server.
Anyone have a idea?
Tanks