After a few pages the installation process will complete, and you will be presented with a link to your Admin Control Panel. Before clicking this link, you should open up your FTP client application again and browse to the
/core/install folder inside your forums directory.
You should
delete all files and subdirectories here as a security precaution. Doing so will not impact vBulletin's operation on your site. Once you have deleted these files you can return to the installer script and click the link to enter the Administrator Control Panel of your freshly installed vBulletin!