The deletion and listing of user accounts created with Firebase Simple Login has been enabled once again in Forge, and will list the email / password-hash mappings as well as allow you to delete those mappings.
Keep in mind that Firebase only automatically stores an email address / password hash combination for Simple Login, and stores it separately from data in your Firebase so that you don't have to worry about managing that data securely.
This means that if you are storing user account data in your Firebase tree following a structure such as /users/$user, then you can always access the data via Forge (accessed at https://<your-firebase>.firebaseio.com
) and view / modify your data there. I'll follow-up here once we've made progress to the Simple Login account management functionality. Thanks!