One of the issues that our users encounter in making the transition to YourSites from the myJoomla online service - is cleaning up the database tables left behind when uninstalling the myJoomla plugin from their client sites.
When you uninstall the myJoomla plugin from your client sites it doesn't actually uninstall fully. It can leave behind large database tables and also a file in your website root. We have therefore written a small plugin which you install via the Joomla! Extension manager on each client site or by using YourSites itself via YourSites -> Sites -> Extensions -> install (For bulk cleanup). This custom plugin uninstalls the myJoomla (bfnetwork) plugin (if its not already uninstalled), removes it's database tables and then deletes the left over file in your Joomla site root and finally it will uninstall itself so you are left completely clean.
This is the best way to uninstall myJoomla and remove the myJoomla bfnetwork plugin and database tables. Best of all, even if you are using another service or no service at all we have provided the plugin free of charge since we don't believe any user should be left with database tables from a service they no longer use or require. As always, if you need any help or support user the discussion forums :-)