'Delete tags from a resource.
:param resource_ids: Resource IDs to be tagged. The resource IDs must
all be associated with the resource_type.
For example, for virtual machines (UserVm) you
can only specify a list of virtual machine IDs.
:type  resource_ids: ``list`` of resource IDs
:param resource_type: Resource type (eg: UserVm)
:type  resource_type: ``str``
:param tag_keys: A list of keys to delete. CloudStack only requires
the keys from the key/value pair.
:type  tag_keys: ``list``
:rtype: ``bool``'

def ex_delete_tags(self, resource_ids, resource_type, tag_keys):

    params = {'resourcetype': resource_type, 'resourceids': ','.join(resource_ids)}
    for (i, key) in enumerate(tag_keys):
        params[('tags[%s].key' % i)] = key
    self._async_request(command='deleteTags', params=params, method='GET')
    return True
