delete inatallation files error - Joomla! Forum - community, help and support

in last screen of installation after clicking on delete installation files displaying error,
and when open localhost/mysite installation starting first screen. manually deleted installation folder. after opening localhost/mysite saying configuration file not found.

its telling ever have done configuration.php file controls joomla either not installed or has not been set during installation progress properly. seem new joomla , have started installation process suggest uninstalling , doing fresh installation instead of looking around config file.