16.5.
$ oc get subscription.operators.coreos.com serverless-operator -n openshift-serverless -o yaml | grep currentCSV
currentCSV: serverless-operator.v1.28.0
$ oc delete subscription.operators.coreos.com serverless-operator -n openshift-serverless
subscription.operators.coreos.com "serverless-operator" deleted
$ oc delete clusterserviceversion serverless-operator.v1.28.0 -n openshift-serverless
clusterserviceversion.operators.coreos.com "serverless-operator.v1.28.0" deleted