Editing a user should be easy.
The tenancy admin uses the Admin > Settings Menu
Find the user in the list and click on their name
You can the edit:
- First Name
- Last Name
- Job Title
- Email Address
- Default Business
- AD User Name
- Whether they are a Tenancy admin or not
The one thing you cannot edit is the login name. If this is incorrect, ie the email address used is wrong, let us know using a support ticket.