code: function(conversationId, properties, callback) {
        conversationId = utils.toUUID(conversationId);
        if (!conversationId) return callback(new Error(utils.i18n.conversations.id));
        utils.debug('Conversation deleteMetadataProperties: ' + conversationId);
  
        var operations = [];
        Object.keys(properties).forEach(function(property) {
          if (property !== 'metadata' && property.indexOf('metadata.') !== 0) {
            property = 'metadata.' + property;
          }
          operations.push({
            operation: 'delete',
            property: property,
          });
        });
  
        edit(conversationId, operations, callback);
      }
docs: Delete metadata on a conversation
  
  @param  {String}   conversationId  Conversation UUID
  @param  {Object}   properties      Properties object
  @param  {Function} callback        Callback function