I installed the wpmu-dev-facebook and now I have a fatal erro

I installed the wpmu-dev-facebook and now I have a fatal error with the chat plugin that says,

"Fatal error: Cannot redeclare class Facebook in /home/content/59/9285459/html/wp-content/plugins/wordpress-chat/lib/facebook-php-sdk/facebook.php on line 93"

what do I do to fix it? I can't even login anymore, should I delete a plugin with ftp?

http://inewstv.org