https://supportforums.cisco.com/thread/2147713
On the back of this previous post I have a new question.
Can I reset ONLY the ASDM http username and password? The previous admin didn't leave it behind (that I can find), but it must have been set up since blank/blank doesn't work.
Thanks
Bryce
Nevermind... figured it out.
Leave the username blank and use the Enable password.