How do I reset all Roundcube email accounts back to default settings?

[Rob Swan]

The simplest way to do this is using PuTTY, but exercise some cation here, if you do this ALL custom settings with be deleted.

In PuTTY, simple issue this command.
sudo mysql -u root -e "DELETE FROM roundcube.users;"

After doing this you will need to log into each of your email accounts and set them up again within Roundcube.