code: public void unregisterWorkflowDef(String name, Integer version) {
          Preconditions.checkArgument(StringUtils.isNotBlank(name), "Workflow name cannot be blank");
          Preconditions.checkNotNull(version, "Version cannot be null");
          delete("metadata/workflow/{name}/{version}", name, version);
      }
docs: Removes the workflow definition of a workflow from the conductor server.
  It does not remove associated workflows. Use with caution.
  
  @param name    Name of the workflow to be unregistered.
  @param version Version of the workflow definition to be unregistered.