In ADE, Ctrl-Shift-D (Windows) or Cmd-Shift-D (Mac) will remove the activation, and allow you to reactivate with a different ID when you launch ADE again.
I had not used an email when I installed ADE on my Mac, which it said then that it wouldn't work with anything but the computer.
Since then, I've bought a Nook and would like it to work with ADE. But your suggestion of keystrokes doesn't help.
So maybe I need to remove all references to ADE on the computer to redo the whole thing. How do I do that?