Remove default › between breadcrumbs in panels breadcrumbs
If you have your own custom theme (or a sub-theme you can edit), you can override theme_breadcrumb(). Actually I'm not sure this is completely supported by panels_breadcrumbs but I assume it is.

THEMENAME_breadcrumb() {
  $breadcrumb = $variables['breadcrumb'];

  if (!empty($breadcrumb)) {
    // Provide a navigational heading to give context for breadcrumb links to
    // screen-reader users. Make the heading invisible with .element-invisible.
    $output = '&lt;h2 class="element-invisible"&gt;' . t('You are here') . '&lt;/h2&gt;';

    $output .= '&lt;div class="breadcrumb"&gt;' . implode(' CUSTOM SEPARATOR ', $breadcrumb) . '&lt;/div&gt;';
    return $output;
  }
}


EDIT:
Alternatively, there are other breadcrumb-customizing modules that allow to specify a custom separator between the breadcrumb items.