code: def delete_access_key(self, access_key_id, user_name=None):
          
          params = {'AccessKeyId' : access_key_id}
          if user_name:
              params['UserName'] = user_name
          return self.get_response('DeleteAccessKey', params)
docs: Delete an access key associated with a user.
  
          If the user_name is not specified, it is determined implicitly based
          on the AWS Access Key ID used to sign the request.
  
          :type access_key_id: string
          :param access_key_id: The ID of the access key to be deleted.
  
          :type user_name: string
          :param user_name: The username of the user