This must be a major security issue. One thing is to be able to that from the backend but from front end is a disaster. I have not found any documentation about how to remove this neither. I would like to see how I disable this "feature" both from backend and frontend before I dare to use this extention.
Except from that the extension looks great and work fine
Don't worry. Its only you (admin) who can see this "Login as Uername" at the front end.
Its only displayed on same computer where you have logged in as administrator. As soon as you log out link goes out.
No other user users or guest will able to login.