Organizing and accessing contact information in Outlook.com
I have the same problem. I can edit everything except phone numbers and emails - I can add but not delete. Even overwriting doesn't work - it just saves the new information along with the old, leaving the old as default - not what I need or want! The only workaround I have found is to create a new contact with the necessary information and delete the old one - but this isn't feasible when you have a large number of updates to make, and it shouldn't be necessary anyway.