The detail steps of deauthorization workflow is posted at, https://blogs.adobe.com/ebooks/2015/04/30/deactivating-a-device-from-your-ade-account/
You can download the latest version of ADE from, Download | Adobe Digital Editions
Thank you for reply. Related deauthorization workflow works in case there is a valid Apple ID and password. However, the problem is more severe if you have forgotten Adobe ID password and you have an email account associated which one doesn't anymore have an access so that Adobe ID can be retrieved.
Is there any possibilty to overcome this situation?