um_fetch_user not working – unable to approve a pending member programmatically

Hi there,

What is the right way to approve a newly registered pending member programmatically?

The below code does not work.

global $ultimatemember;
um_fetch_user( $user_id );
UM()->user()->approve();

and also this approach does not work in a page template.

global $ultimatemember;
um_fetch_user($user_id);
$ultimatemember->user->approve();