Actually, It's a good idea to remove that. If SSL isn't working as expected, then this can actually break things.
There's a discussion about this at https://forum.bytemark.co.uk/t/https-rather-than-http/2685/5
But, to summarise, make sure you have a good working https:// site first.
When you're confident about that, then you're ready to set up a redirect. Add the ssl-only file, then run symbiosis-httpd-configure and then edit the configuration file for your site, which you'll find in /etc/apache2/sites-enabled and change max-age=15768000 to something short. Perhaps 0. Then run "service apache2 reload"
Then check the HTTP redirect. It should happen on the server. And, if the site works nicely with redirections in place, and only then, should you change the max-age back, so that redirection will in future take place in the browser. Oh, and test that, too!