like backups, volume, engine etc...

I can't change the finalizers on those resources somehow.

probably because there is no longhorn stuff anymore in the cluster...

for example

error: <http://volumeattachments.longhorn.io|volumeattachments.longhorn.io> "pvc-057dbf6d-cdbc-417b-b743-a73a85a49d42" could not be patched: Internal error occurred: failed calling webhook "<http://mutator.longhorn.io|mutator.longhorn.io>": failed to call webhook: Post "<https://longhorn-admission-webhook.longhorn-system.svc:9502/v1/webhook/mutation?timeout=10s>": service "longhorn-admission-webhook" not found

I finally did it I believe.... I had to delete the mutating and validating hooks created by longhorn. Then I was able to change the finalizers of all the remaining resources in the namespace...

k delete <http://validatingwebhookconfigurations.admissionregistration.k8s.io|validatingwebhookconfigurations.admissionregistration.k8s.io> longhorn-webhook-validator

k delete <http://mutatingwebhookconfigurations.admissionregistration.k8s.io|mutatingwebhookconfigurations.admissionregistration.k8s.io> longhorn-webhook-mutator

for type in $(kubectl api-resources --namespaced=true --verbs=delete -o name | grep longhorn); do echo $type; for res in $(kubectl get $type -o name); do kubectl patch $res -p '{"metadata":{"finalizers":[]}}' --type=merge; done; done;

that's what it took to clean up my own mess...