Force HTTPS and non-www domain via .htaccess file

RewriteEngine On

# match any URL with www and rewrite it to https without the www
RewriteCond %{HTTP_HOST} ^(www\.)(.*) [NC]
RewriteRule (.*) https://%2%{REQUEST_URI} [L,R=301]

# match urls that are non https (without the www)
RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} !^(www\.)(.*) [NC]
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Don't forget to put the snippet at the top of the .htaccess file.

All thanks go to StackOverflow answer here.