It is not possible to change another user's information. Only the user themselves can change profile information. Please support this idea in our forum for the ability for admins to change user profile information.
How users can change their profile information
If someone needs to update their display name, email address or password they can do so from the web portal, by clicking the "Settings" link:
They can change their display name, email address, title, language and reset their password.
Admins and agents can also change their user information in "My profile" settings, in the upper left of the admin console, see this article for more information.
Q: Can I delete a user?
A: Yes, you can! Learn more here.
Q: Can I block a user?
A: Yes! Learn how here.