It may not happen often but if you ever need to update the record of a disabled user, it might involved assigning a license temporarily. If you don't have extra licenses available or if you don't want to add a new license to your subscription just for this purpose, there is a way around it. Like other record types in CRM, you can import changes to user records. All you have to do is export the specific user and the fields that need to be changed, make the changes in Excel, then re-import your changes. It's that simple! You could also achieve the same results by using a workflow to update your records.
Keep in mind that some fields can still only be edited in Office 365, like first and last name, title, etc.