Like I said this is dependent on you having your functioning certificate
server {
listen 443 ssl;
# add ssl settings here
server_name www.example.com;
return 301 http://www.example.com;
}
EDIT: only redirecting only the root URL
server {
listen 443 ssl;
# add ssl settings
location = / {
return 301 http://www.example.com;
}
}