Ok, I got it to work like so:
SQL> select object_id from acs_objects where creation_user = 20723;
OBJECT_ID
----------
20797
20798
SQL> begin
2 content_folder.delete(20798);
3 content_folder.delete(20797);
4 acs.remove_user(20723);
5 end;
6 /
(the key being to do the folders in reverse order). More than a bit klunky, but maybe this will help someone.
