Attempt to Delete a plugin crashed the site

We are using Zen Cache now, so attempted to delete WP Super Cache, and the site crashed with this error message: Fatal error: Call to undefined function nocache_headers() in /home/chris245/public_html/wp-admin/admin.php on line 33
Both the admin and the actual site are down.( http://www.ChristCenteredLeaders.org). Thank you.