If your platform is new
1.boot_ontap then ctrl-c to boot menu, select Option 9, go to Advanced Drive Partitioning Boot Menu Options
2. Run 9a on each node
3. After 9a is executed on all nodes, execute 9b on each node
4. Wait for all nodes to appear
Welcome to the cluster setup wizard
If your platform is old
The node configuration needs to be erased to the factory default Settings
How to decommission or repurpose an HA Pair with ONTAP 9 - NetApp Knowledge Base