This will come up with a value of 0 if there are no jobs running or in queue.
SELECT COUNT(*) WORKFLOWS_NOT_INACTIVE FROM "ODMRSYS"."ODMR$WORKFLOWS" WHERE status NOT IN ('INACTIVE','STOPPED','STOPPING');
If there were workflows that were stuck in queued state, and they could not be canceled via Data Miner, then the workflow records in the ODMr repository will need to be manually updated prior to dropping the repository.
select * from "ODMRSYS"."ODMR$WORKFLOWS";
After that, you should be able to drop the repository and reinstall.
UPDATE "ODMRSYS"."ODMR$WORKFLOWS" SET STATUS = 'INACTIVE'; COMMIT;