code: func (c *Challenge) CleanUp(authz acme.Authorization) error {
  	log.Infof("[%s] acme: Cleaning DNS-01 challenge", challenge.GetTargetedDomain(authz))
  
  	chlng, err := challenge.FindChallenge(challenge.DNS01, authz)
  	if err != nil {
  		return err
  	}
  
  	keyAuth, err := c.core.GetKeyAuthorization(chlng.Token)
  	if err != nil {
  		return err
  	}
  
  	return c.provider.CleanUp(authz.Identifier.Value, chlng.Token, keyAuth)
  }
docs: // CleanUp cleans the challenge.