+ db.delete_index(table_name, column_names, db_tablespace='')
+Deletes an index created by db.create_index or one of the other South
+functions. Pass the column_names in exactly the same order as the other call
+to ensure this works; we use a hashing algorithm to make sure you can delete
+migrations by only specifying column names.
+db_tablespace is an Oracle-specific option.
+Deleting an index on 'name'::
+ db.delete_index('core_profile', ['name'])
+Deleting the unique index on the combination of 'name' and 'age' columns
+(from the db.create_index examples)::
+ db.delete_index('core_profile', ['name', 'age'])