Erasing Authorization ADE without a password

OK, I will try to keep this as clear as possible. Here's the circumstances:

I have a Kobo, and I use Adobe Digital Editions to put ebooks I've borrowed from the library on it. I've done this for years. Then my Kobo died, and I just used the overdrive app on my phone for library books.

Last year moved, switched internet providers, and lost my old email. Luckily, I had a shiny new gmail account that I changed almost everything to, and everything has been great. I changed my Adobe ID to my new email.

I got a new Kobo a couple months ago, and the first couple library books I put on it were fine.

Then, I transferred a batch of library books from computer to Kobo, and I got a message on the Kobo saying that 'My reader is not authorized to open this book... re-authorize your e-Reader with your Adobe ID using Adobe Digital Editions'. Fine. Stuff like that happens.

So I went into ADE and find that the account it is authorized to is my OLD email. And because that is no longer a valid Adobe login, I can't log in. (although, it only tells me my password is wrong, not the login, but I've got the password right.)

Fine, I thought I'd just de-authorize the computer, and re-authorize with my current Adobe ID. But you need a valid login/password for that!

I tried deleting everything I could find of ADE from my computer, and reinstalling it, but somehow it still remembers the wrong email.

I can read the books fine on my desktop, the problem is I need to re-auth my Kobo, and I can't do that because ADE thinks an email that is long gone still exists.

I've tried everything I can think of! Help me please, I mostly read library books, not Kobo store books!