DELETE VARIABLES deletes the specified variables from the dictionary.
DELETE VARIABLES var_list.
DELETE VARIABLES should not be used after defining transformations
but before executing a procedure. If it is used in such a context, it
causes the data to be read. If it is used while TEMPORARY is in
effect, it causes the temporary transformations to become permanent.
DELETE VARIABLES may not be used to delete all variables from the
dictionary; use NEW FILE to do that (see NEW FILE).