repmgr witness unregister removes a witness server's node record from the repmgr metadata.
The node does not have to be running to be unregistered, however if this is the case then either provide connection information for the primary server, or execute repmgr witness unregister on a running node and provide the parameter --node-id with the node ID of the witness server.
Execute with the --dry-run option to check what would happen without actually registering the witness server.
Unregistering a running witness node:
$ repmgr -f /etc/repmgr.conf witness unregister
INFO: connecting to witness node "node3" (ID: 3)
INFO: unregistering witness node 3
INFO: witness unregistration complete
DETAIL: witness node with UD 3 successfully unregistered
Unregistering a non-running witness node:
$ repmgr -f /etc/repmgr.conf witness unregister -h node1 -p 5501 -F
INFO: connecting to node "node3" (ID: 3)
NOTICE: unable to connect to node "node3" (ID: 3), removing node record on cluster primary only
INFO: unregistering witness node 3
INFO: witness unregistration complete
DETAIL: witness node with id ID 3 successfully unregistered
This command will not make any changes to the witness node itself and will neither remove any data from the witness database nor stop the PostgreSQL instance.
A witness node which has been unregistered, can be re-registered with repmgr witness register --force.