If you are not familiar with the oc command, refer to OpenShift - Getting Started with the oc command.

By default, Cluster Logging Management State should be Managed.

~]$ oc get clusterlogging instance --namespace openshift-logging
NAME       MANAGEMENT STATE
instance   Managed

Which can also be seen in the Cluster Logging Instance YAML.

~]$ oc get clusterlogging instance --namespace openshift-logging --output yaml
apiVersion: v1
items:
- apiVersion: logging.openshift.io/v1
  kind: ClusterLogging
  spec:
    managementState: Managed

The oc patch command can be used to update the Management State to Unmanaged.

~]$ oc patch clusterlogging instance --namespace openshift-logging --type merge --patch '{"spec":{"managementState":"Unmanaged"}}'
clusterlogging.logging.openshift.io/instance patched

Now, the Cluster Logging Management State should be Unmanaged.

~]$ oc get clusterlogging instance --namespace openshift-logging
NAME       MANAGEMENT STATE
instance   Unmanaged

Which can also be seen in the Cluster Logging Instance YAML.

~]$ oc get elasticsearch --namespace openshift-logging --output yaml
apiVersion: v1
items:
- apiVersion: logging.openshift.io/v1
  kind: ClusterLogging
  spec:
    managementState: Unmanaged