Drops feature(s) from the original FeatureList and returns a new FeatureGroup object.
>>> feature_list = fb.FeatureList([
... catalog.get_feature("InvoiceCount_60days"),
... catalog.get_feature("InvoiceAmountAvg_60days"),
... ], name="feature_lists_invoice_features")
>>> amount_only_feature_list = feature_list.drop(["InvoiceCount_60days"])