The GVO Manager can manage the GVO settings for a user and this includes swapping the authentication method from being App based to being email based - useful if the user does not have a smart device.
A GVO Manager has access to change the user profile settings of all users. This includes the MFA settings for that user.
To change MFA settings for a user go to the user profile and edit.
Navigate to the MFA section where the available options will be shown.
NOTE: If the user has not registered for MFA then the only option will be to add email authentication (usually because the user does not have access to a smart device/authenticator).
Most users will use the App based authentication method (more secure) here is the option to switch email based authentication (and code is sent to the email account). If the user is already using email based authentication the list of options looks like this to allow switching to App based.
Note: It is not possible to remove MFA settings if the user has an account in a GVO where MFA is 'Required'.
Help about MFA is here - MULTI-FACTOR AUTHENTICATION HELP