It would be great to understand why your deployment of HA Cluster with Keystone failed; for most of the OpenStack API services (Cinder, Glance, Nova Cloud Controller and Keystone), a VIP (Virtual IP) is required to complete clustering - for example:
juju set keystone vip=192.168.22.1
The relation between HA Cluster and Keystone will fail to establish with a hook error if this is not supplied. If you did not provide this prior to relating HA Cluster with Keystone, you can set it as described above and resolve/retry the relation that failed:
juju resolved --retry keystone/0
Hopefully this will resolve the error and result in a functioning, clustered Keystone.
As your cluster never formed, your should also be able to remove the relation between HA Cluster and Keystone; however your will have to manually resolve any failed relations before Juju will let you do this:
juju resolved keystone/0
juju remove-relation keystone hacluster
Note that if you had managed to form a cluster removing the relation will not de-cluster the service; it locks in the configuration.