Problem with auto discovery

Hey, I had a few problems with my auto discovery, I cannot remember my password and I have no clue how I should reset the password, because when I'm reinstalled it, it had the same machine name and all the options was like before the reinstallation... so the best way in my opinion would be to reset the password in somehow or make a new passage which I cannot figure out how to do.

Does anyone have any clue how I should remove my machine name so I can make a new connection, or reset the password?
//Alinyo