How to remove "index.php" in codeigniter's path

I found that I was not changing AllowOverride None to AllowOverride All in my virtual host file at /etc/apache2/sites-available/default

<VirtualHost *:80>
    ServerAdmin webmaster@localhost

    DocumentRoot /var/www
    <Directory />
            Options FollowSymLinks
            AllowOverride All    <---- replace None with All
    </Directory>
    <Directory /var/www >
            Options Indexes FollowSymLinks MultiViews
            AllowOverride All   <---  replace None with All
            Order allow,deny
            allow from all
    </Directory>
    
     ...

This will work:

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* index.php/$0 [PT,L]