You’ll typically use a block storage volume when you want data to persist after a container process exits. If you delete volumes with kubectl using the pv, pvc, or pod option, the block storage volume will be permanently deleted.
When you’ve deleted a cluster from the control panel, the volume will not be automatically deleted and billing will continue. In this case, visit the control panel and manually delete the block storage volume.
Note that while you can currently delete block storage volumes and load balancers from the control panel, we recommend that you use kubectl to manage all cluster-related resources.
For more about managing persistent volumes see:
Other Kubernetes Components in the DigitalOcean Community’s Introduction to Kubernetes.
Kubernetes Objects in the official Kubernetes Concepts guide
Persistent Volumes in the official Kubernetes Storage guide