First of all – Please make sure that you have installed version 1.8 or newer of Beaver Builder plugin.
Meanwhile, to get back your website in working condition, please deactivate the UABB plugin and remove it manually through your FTP program.
- Login to the site via your FTP Program.
- Go to the WordPress plugins directory and find bb-ultimate-addon folder.
- Delete the bb-ultimate-addon folder from your server.