Fatal error: Cannot redeclare sydney_set_import_files()

I updated the sydney tool box plugin and now I cannot access the site or admin page as it now comes up with the following whenever i enter the page address.

Fatal error: Cannot redeclare sydney_set_import_files() (previously declared in /homepages/3/d725465542/htdocs/TeamPartnership/wp-content/plugins/sydney-toolbox/demo-content/setup.php:18) in /homepages/3/d725465542/htdocs/TeamPartnership/wp-content/themes/sydney/demo-content/setup.php on line 20

I am helping someone else update their website and now it has crashed, help would be highly appreciated in these circumstances.

The page I need help with: [log in to see the link]