Configuring preferences and options in Outlook.com
Other people are reporting this same problem ....
PLEASE NOTE:
This issue is NOT about managing/cleaning-up auto-suggestions of addresses that are in ones contacts.
This issue involves the inability to manage/clean-up auto-suggestions that are NOT from ones contacts. For those auto-suggested addresses that are NOT from ones contacts, there is no way to change or delete an address (i.e., an address that is no longer valid, an address with a typo in it, etc).
Since this bug involves addresses that are NOT from ones contact list, telling customers to enable the option to Only suggest people in my contact list is not a valid solution.
This is clearly a bug or a design flaw. Others have also reported this problem.
YOU NEED TO ESCALATE THIS TO MICROSOFT.