Once you delete the email address listed on the BlackBerry ® Messenger, you can no longer restore your contact list over the wireless network using the email address. If you delete all the registered email address from BlackBerry Messenger, then your contact list will not automatically backed up again until you register the email address on BlackBerry Messenger.
Here's How to Delete Email Addresses Listed on BlackBerry Messenger:
1. On the Home screen or in the Instant Messaging folder, click the BlackBerry Messenger icon.
2. On the contact list screen, press the Menu key.
3. Click Options.
4. Click the Backup.
5. Click the Back up files remotely.
6. On the Backup screen, highlight an email address.
7. Press the Menu key.
8. Click the Edit Email Status.
9. Press the Menu key.
10. Click the Disable email.