Read: https://olm.operatorframework.io/docs/tasks/uninstall-operator/
To run before removing an operator, because operator's owned resources may not be removed to avoid data loss.
$ oc get csv cert-manager-operator.v0.15.3 \
-o=jsonpath='{"customresourcedefinitions: "}{.spec.customresourcedefinitions.owned[].name}{"\n"}{"apiservicedefinitions: "}{.spec.apiservicedefinitions.owned[].name}{"\n"}'
Output:
customresourcedefinitions: certmanagers.operator.cert-manager.io
apiservicedefinitions: