public function unregisterNamespace($prefix)
{
if (isset($this->coreNamespaces[$prefix])) {
throw new NamespaceException("Cannot unregister JCR core namespace prefix '{$prefix}'.");
}
$this->ensureNamespacesBackup();
$this->getConnection()->delete('phpcr_namespaces', array('prefix' => $prefix));
if (!empty($this->namespaces)) {
unset($this->namespaces[$prefix]);
}
}