WordPress.org

My admin account for WP doesn't work anymore!

We're authenticating externally, right? Take that admin account you initially created in your WP setup and make sure it's in your external database. Once it's in there you'll be able to log in as admin with no problems. If you can't do this, delete the plugin and it'll restore access using your WP admin account.

Can I still create accounts within WordPress?

You could, but they don't work properly as it's not checking against the WP database, just the external then making sure the WP user info is the same as what's currently on the external database.

Can I update user information within WordPress?

Nope.

My external database's passwords are hashed with a salt/datestamp/phases of the moon/etc

Choose "Other" as your encoding method, then enter the method you use in the "Other" textbox as PHP code. If it involves more than the username and password, though, you may need to modify the plugin source code.

I'm locked out!

Delete or rename the plugin; if it's a DB connection-related error most likely you have the wrong connection, etc. information for the external database.