Proposed title of this feature request

Requirement is to prune OCP users and identities objects if they are not found in the upstream identity provider periodically.

In the documentation[1], we provided the features to prune groups through oc command but we don't have anything for users and identities.  

$ oc adm prune groups --sync-config=/path/to/ldap-sync-config.yaml --confirm

Why does the customer need this?

As stated, we have several OCP clusters and need to clear up hundreds of old records across the clusters. 

[1]https://docs.openshift.com/container-platform/4.9/authentication/ldap-syncing.html