@Override
    public String invoke() throws AmbariException {
      String clusterName = getClusterName(properties);
      String alias = getAlias(properties);
      credentialStoreService.removeCredential(clusterName, alias);
      return alias;
    }
DeleteResourcesCommand implements a Command that performs the steps to delete existing credential
resources. Credential resources will be deleted from both storage facilities, if necessary.
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/CredentialResourceProvider.java