code: function(cb) {
              // do it in parallel
              async.eachSeries(relations,
                function(item, cb) {
  
                  var collection = connectionObject.collections[item];
                  if (!collection) return cb(Errors.CollectionNotRegistered);
  
                  collection.dropTable(function(err) {
                    // ignore "table does not exist" error
                    if (err && err.code === 8704) return cb();
                    if (err) return cb(err);
                    cb();
                  });
                },
                function(err, results) {
                  if (err) return cb(err);
                  cb();
                }
              );
            }
docs: drop relations