TRy below steps:
Transfer any book from your phone to your machine [ADE]
DOuble click on the book
ADE will prompt for authorization as book authorization is different from current ADE auth
Enter new credentials [that you used on your phone to authorize it]
ADE will now be authorized with two id's [old and new]
or
follow below steps:
Note: if you follow below steps, you will not be able to authorize ADE with old email id again as you don't know the password.
Follow these steps if you really want to deauthorize old credentials.
Mac:
1. Go-> Go to folder.
Go to folder dialog will appear.
2. Type ~/Library/Application Support/Adobe/Digital Editions
drag the activation.dat file to the trash.
ADE will be deauthorized now.
Now Authorize ADE again [Help -> Authorize Computer].
Windows:
Choose Start > Run.
In the Open text box, type regedit and then press Enter. The Registry Editor opens.
In the left pane of the Registry Editor, locate the following registry key:
HKEY_CURRENT_USER\Software\Adobe\Adept
Right-click the Adept key and choose Delete.
In the Confirm Key Delete dialog, click OK.
Your authorization will be deleted.
ADE will be deauthorized now.
Now Authorize ADE again. [Help -> Authorize Computer].