chef_rest_delete.rb

#!/usr/bin/ruby

require 'chef'
require 'chef/rest'

Chef::Log.debug("Authenticating via openid") 
response = @rest.post_rest('openid/consumer/start', { 
  "openid_identifier" => "#{Chef::Config[:openid_url]}/openid/server/node/program_auth",
  "submit" => "Verify"
})
@rest.post_rest(
  "#{Chef::Config[:openid_url]}#{response["action"]}",
  { "password" => 'your_pw' }
)

Chef::REST.delete_rest("#{Chef::Config[:registration_url]}/nodes/#{'your node name'}")