How to force delete resources in a non-existant namespace? - kubernetes

Question

This question is a follow up of: How to list really all objects of a nonexistant namespace?
Long story short:
$ kubectl get namespaces
NAME STATUS AGE
argo Active 27d
default Active 27d
kube-node-lease Active 27d
kube-public Active 27d
kube-system Active 27d
$ kubectl get eventbus -n argo-events
NAME AGE
default 17h
$ kubectl get eventsource -n argo-events
NAME AGE
pubsub-event-source 14h
There are two resources in namespace argo-events which actually no longer exits because I deleted it and expected it to be gone with all resources in it. Obviously something didn't work as expected.
Now (after listing potentially more objects - first question) I want to really get rid of those resources because they seem to block a redeployment.
But this ...
$ kubectl delete eventbus default -n argo-events
eventbus.argoproj.io "default" deleted
^C
$ kubectl delete eventsource pubsub-event-source -n argo-events
eventsource.argoproj.io "pubsub-event-source" deleted
^C
... doesn't work.
So, how do I force their deletion?
UPDATE:
$ kubectl describe eventbus default -n argo-events | grep -A 3 final
f:finalizers:
.:
v:"eventbus-controller":
f:status:
$ kubectl describe eventsource pubsub-event-source -n argo-events | grep -A 3 final
f:finalizers:
.:
v:"eventsource-controller":
f:spec:

Answer 1

This worked:
$ kubectl create namespace argo-events
namespace/argo-events created
$ kubectl patch eventsource/pubsub-event-source -p '{"metadata":{"finalizers":[]}}' --type=merge -n argo-events
eventsource.argoproj.io/pubsub-event-source patched
$ kubectl patch eventbus/default -p '{"metadata":{"finalizers":[]}}' --type=merge -n argo-events
eventbus.argoproj.io/default patched
$ kubectl delete namespace argo-events
namespace "argo-events" deleted
If somebody stumbles upon this answer and knows why this works - please add an explanation in a comment. That would be cool, thanks.

Answer 2

What about:
kubectl delete eventsource pubsub-event-source -n argo-events --grace-period=0 --force
?