php - Remove values with null from laravel api

one text

I have an api that fetches data of users who are admins of certain groups. But the api is returning all the users and displaying null on the groups. How can I get rid of the users with the null groups and query only the group admins? Thank you

Here is my Eloquent relationship

public function groupadmin()
{
    return $this->hasOne(Group::class, 'admin_id', 'id');
}

And the Controller

public function users()
{
    $user = User::with('groupadmin')->get();
    return response()->json([
        'status'=>200,
        'user'=>$user,
    ]);
}

Please help. Thank you