You must be a domain admin to update a user's email.
See the Delete a User from a Workspace/Project section in Disable or Delete Users. whose email you want to update.
- Use the API for updating a user's information.
- In the resource, specify the user ID.
In the request body, specify the firstName and lastName mandatory parameters, and the email parameter with the new email address for the user.
After the API call is executed, the email address is updated.