run these commands on the remote server
sudo visudo -f /etc/sudoers.d/winscp
and put the hereunder line, then save
ict ALL=(root) NOPASSWD: /usr/lib/openssh/sftp-server

on WinSCP where is the server connection click Edit-Advanced-Environement-SFTP-SFTP Server and put there the hereunder line then save
sudo /usr/lib/openssh/sftp-server