The job clusters for finished or failed runs are maintained in Job Clusters UI. They are up to 30 recently terminated job clusters are retained in UI and others are terminated. The finished or canceled runs are also cleaned up automatically starting with the oldest terminated cluster first.

One more thing to note, these terminated clusters list maintained in the Datbricks UI is just for config reference or audit of recent runs. These clusters do not link to any cloud resources (VMs, IPs, or Disks). These resources do not incur any actual cost in the cloud.