Prevent email change

I have tried this code, but it wasn’t succesful

add_action('profile_update', 'prevent_email_change', 10, 3);

function prevent_email_change($user_id, $old_user_data)
{
  $user = get_user_by('id', $user_id);

  if ($user->user_email != $old_user_data->user_email)
  {
    $user->user_email = $old_user_data->user_email;
  }
}

add_action('wpmem_pre_update_data', 'user_update_prevent_email');

function user_update_prevent_email($fields)
{
  $user = wp_get_current_user();
  $fields['user_email'] = $user->user_email;
  $_POST['user_email']  = $user->user_email;
}