I'm trying to run the NOOKstudy program but when I try to logging with my B&N account the program tells me that I can log in to my B&N account because the computer is registered with an Adobe ID account. The message suggested me to call Adobe, whish I did. When I called they told me to write in the forum to see if someone had an idea on how to do this.
Ctrl-Shift-D on Windows, Cmd-Shift-D on the Mac.
NOTE: This only removes the activaiton information on your computer, and it does not give you an activation allowance back. Which is to say if you do "unregister and then reactivate with your AdobeID" 6 times, you will have used up all of your activations and will need to contact tech support (http://www.adobe.com/support/digitaleditions - click on 'Submit a web case') to get your activation counts reset.