delete a user schema from cn=config

Hi list,

I was experimenting locally written schema with a recent build of slapd. I added the schema ldif with no problem using

ldapadd -QY EXTERNAL -H ldapi:/// ...

But then I realized I made a mistake, so I try to delete it with

ldapdelete -QY EXTERNAL -H ldapi:///

it says:

ldap_delete: Server is unwilling to perform (53)

what does it mean? The schema is not used by any data on the server. I can use slapmodify to remove it after server shutdown, but that kind of suck and not much different, or even worse than editing conf file?

Derek