WordPress WP Uninstaller plugin by simon99, will delete a WordPress site, once activated can:
delete (or keep) WordPress database tables
delete (or keep) WordPress ‘wp-config.php’ file
delete (or keep) all files and folders in your WordPress directory (yes, that means everything!)
WP Uninstaller uses WordPress nonces, in addition to permission checks, to ensure only administrators can uninstall WordPress. It’s also recommended that you leave the plugin de-activated until you need it.
Download and info: http://wordpress.org/extend/plugins/wp-uninstaller/
