User online plugin upgrade causing fatal error

When I upgraded the UserOnline plugin it cause this error and I can not log into my blog dashboard anymore how can I fix this? I’m assuming I just delete that plugin from the plugins directory and that will fix it and then re-install but I do not want to break anything further or loose anything… help?!

Error:

Fatal error: Call to undefined method scbOptions::get_key() in /home/content/s/t/o/***********l/html/wp-content/plugins/wp-useronline/admin.php on line 56