Changing a user's email address can be done either in the workspace by an admin, or in Account Manager by a main user.
Making the change in Account Manager will change it globally across all workspaces under the particular account, whereas changing the email in a workspace will only apply to that specific workspace.
Changing a user's email immediately logs the user out from all workspaces that the change impacts and disables all previous login links. This occurs due to security reasons to prevent the owner of the old email from accessing the workspace.
To change a user's email in the workspace, the admin must open the user's profile from on the Users page in Workspace Manager:
Change the email address and hit 'Save'.
Once the change is saved, any old login links that user may have had are disabled, and they can only log in to the workspace using the new email address.