'Deletes tags from a resource.
:param resource: The resource to be tagged
:type resource: :class:`Node` or :class:`StorageVolume`
:param tags: A dictionary or other mapping of strings to strings,
specifying the tag names and tag values to be deleted.
:type tags: ``dict``
:rtype: ``bool``'

def ex_delete_tags(self, resource, tags):

    if (not tags):
        return
    params = {'Action': 'DeleteTags', 'ResourceId.0': resource.id}
    for (i, key) in enumerate(tags):
        params[('Tag.%d.Key' % i)] = key
        if (tags[key] is not None):
            params[('Tag.%d.Value' % i)] = tags[key]
    res = self.connection.request(self.path, params=params.copy()).object
    return self._get_boolean(res)
