BuddyPress.org

My “sledgehammer” option assumes you have access to your Database… most likely via PHPMyAdmin. Look for a databases option in your web host control panel. Open the database for your site and look for the wp_sitemeta table near the bottom of the list of tables on the left. Open that table. Then click on the “browse” tab to see the contents of that table. Now look for the “active_sitewide_plugins” row (in the meta_key column). Edit that sucker. Just click on the little pencil. And simply delete the junk that is stored in the “meta_key_value”. This worked for me. But please bear in mind… you’re messing directly with the database! And you do so at your own risk. But again… this worked for me. And it should be pretty safe. Just don’t go editing or deleting other things in there willy-nilly. You could bust the entire site pretty easily.

Maybe make a backup before you start. Right when you open the database… click the “export” tab.