Registry v4.0.0 introduces the concept of Garbage Collection, or delayed background deleting of records. Currently, Garbage Collection only applies to deleting COs.
Garbage Collection is processed by the Core Job Plugin GarbageCollector Job.
Scheduling the Garbage Collector
If deleting a CO generates a "No job of type CoreJob.GarbageCollector available" error, manually reschedule the GarbageCollector job via COmanage CO > Configuration > CO Settings > Garbage Collection > Schedule Job. If a View Job button is present instead, the Job has already been scheduled.