After enabling Unified Login and then are unable to login, these steps allow you to disable Unified Login in the database for the Admin user.
Confirm you have a current backup of the database before making any changes.
The data is stored in HEATINI.Contents where INISection = 'Unified Login Admin'. Here is a query that can be run:
Update HEATINI set Contents = '0' where INISection = 'Unified Login Admin'
You will then be able to go into the Admin Module and change the Unified Login options.