Delete the model expression for a data set.
This removes the model expression, created by set_model, for a data set. It does not delete the components of the expression.
Parameters: id (int or str, optional) – The data set containing the source expression. If not given then the default identifier is used, as returned by get_default_id.
Remove the model expression for the default data set:
Remove the model expression for the data set with the identifier called ‘src’: