Organizing and accessing contact information in Outlook.com
I can't speak for the original poster, but I suspect the situation is the same. Accessing People through https://outlook.live.com/owa/?path=/people , through FireFox or IE (no, Edge is not an option as the machines I've tried this on are not capable of Win 10). Happens with all my Contacts, and NONE of them are linked to any social account. There is no error message at any stage.
When I access the contact the email address is listed down in the "Personal" section in a *gray* box and is uneditable. There is a blank box above it, also labeled Personal which is editable (and clearable, later), but if I type the new address in this box, when I Save, both addresses are listed. Going back in to Edit again, both show, but only the new address can be edited. The original address is still in the untouchable gray box. If I try to send a message to this Contact, both addresses are displayed and the original one is checked and seems to be the 'default' that will be used (which is why I need to change it!).
There seems to be no way to get rid of the original address without deleting the Contact completely, which is an unacceptable situation.