You can manually edit any user name and email address in Receptive.
If the user was created through the Receptive API, you can change their details with the instructions here.
Find the user's account page either by using the search bar at the top, or by heading to the "Customers" link on the left-hand navigation and selecting the relevant customer from the list.
Click the "Edit" button next to their avatar.
Then edit any details as necessary. Click on "Save Changes" to ensure your changes take place.