Not able to completely remove Kubernetes CustomResource

$ kubectl get crd

NAME                                                            CREATED AT
accesscontrolpolicies.networking.zephyr.solo.io                 2020-04-22T12:58:39Z
istiooperators.install.istio.io                                 2020-04-22T13:49:20Z
kubernetesclusters.discovery.zephyr.solo.io                     2020-04-22T12:58:39Z
meshes.discovery.zephyr.solo.io                                 2020-04-22T12:58:39Z
meshservices.discovery.zephyr.solo.io                           2020-04-22T12:58:39Z
meshworkloads.discovery.zephyr.solo.io                          2020-04-22T12:58:39Z
trafficpolicies.networking.zephyr.solo.io                       2020-04-22T12:58:39Z
virtualmeshcertificatesigningrequests.security.zephyr.solo.io   2020-04-22T12:58:39Z
virtualmeshes.networking.zephyr.solo.io                         2020-04-22T12:58:39Z

$ kubectl delete crd istiooperators.install.istio.io

delete error

$ kubectl patch crd/istiooperators.install.istio.io -p '{"metadata":{"finalizers":[]}}' --type=merge
success delete crd istiooperators.install.istio.io

result

NAME                                                            CREATED AT
accesscontrolpolicies.networking.zephyr.solo.io                 2020-04-22T12:58:39Z
kubernetesclusters.discovery.zephyr.solo.io                     2020-04-22T12:58:39Z
meshes.discovery.zephyr.solo.io                                 2020-04-22T12:58:39Z
meshservices.discovery.zephyr.solo.io                           2020-04-22T12:58:39Z
meshworkloads.discovery.zephyr.solo.io                          2020-04-22T12:58:39Z
trafficpolicies.networking.zephyr.solo.io                       2020-04-22T12:58:39Z
virtualmeshcertificatesigningrequests.security.zephyr.solo.io   2020-04-22T12:58:39Z
virtualmeshes.networking.zephyr.solo.io                         2020-04-22T12:58:39Z

So it turns out , the root cause was that Custom resources with finalizers can "deadlock". The CustomResource "functions.kubeless.io" had a

Finalizers: customresourcecleanup.apiextensions.k8s.io

and this is can leave it in a bad state when deleting.

https://github.com/kubernetes/kubernetes/issues/60538

I followed the steps mentioned in this workaround and it now gets deleted. Hope this helps anyone else who runs into this.