'Delete a policy.
:type policy_name: str
:param policy_name: The name or ARN of the policy to delete.
:type autoscale_group: str
:param autoscale_group: The name of the autoscale group.'

def delete_policy(self, policy_name, autoscale_group=None):

    params = {'PolicyName': policy_name}
    if autoscale_group:
        params['AutoScalingGroupName'] = autoscale_group
    return self.get_status('DeletePolicy', params)
