Delete Adobe ID?

Hi.

Recently, when downloading books from ebooks.com I was told that I didn't have an Adobe account.  This wasn't the case but couldn't continue without one so I went ahead and created one.

Now my sony eBook doesn't work and I cannot open any new books on my computer.

How do I delete my new account and revert to the old one?

Any assistance would be gratefully received.

Thanks,

mark.