If your WAN Edge devices (SSR) no longer need to operate as a High Availability (HA) cluster, you can delete the HA cluster from the Juniper Mist portal. The WAN Edge devices are automatically reprovisioned as standalone devices and remain available in the inventory.
Cannot delete an SSR cluster.
How to delete an SSR HA cluster
Steps to delete an SSR Cluster:
After the HA cluster is deleted:
Delete a High Availability Cluster | Mist | Juniper Networks