Form submit handler to delete a browser language negotiation mapping.
function language_negotiation_configure_browser_delete_form_submit($form, &$form_state) {
$browser_langcode = $form_state['browser_langcode'];
$mappings = language_get_browser_drupal_langcode_mappings();
if (array_key_exists($browser_langcode, $mappings)) {
unset($mappings[$browser_langcode]);
language_set_browser_drupal_langcode_mappings($mappings);
}
$form_state['redirect'] = 'admin/config/regional/language/detection/browser';
}