I believe the only way is through deleting the DB record for it,
please contact GSS (file a support request) for the supported way on how to do this.
Hi, instead of deleting the record in the DB I would rather delete it through the metamodel.svc service. Is it a DEM Orcehstrator or DEM Worker? You would either have a look at $metamode.DEMs or $metamodel.DEMActiveOrchestrators to find out what's wrong.