How to remove public/index.php from the URL

Thanks for your reply

I have no public_html folder at all. I have one folder (named as my domain) and that is the root folder. And inside I have all my files and folders as they has been downloaded from CodeIgniter. 

--mydomainname
  -.well-known
  -app
  -cgi-bin
  -public
  -system
  -writable
  .env 
  .robots.txt

And I am still getting that 403 Forbidden error. So, how should I change my folder structure, or my .env file to get rid of the error?