If a namespace on Kubernetes is stuck on the ’terminating’ / finalizer state. You can try to run the following to delete it.

read -p "Namespace: " NAMESPACE
kubectl proxy &
kubectl get namespace $NAMESPACE -o json |jq '.spec = {"finalizers":[]}' >temp.json
curl -k -H "Content-Type: application/json" -X PUT --data-binary @temp.json 127.0.0.1:8001/api/v1/namespaces/$NAMESPACE/finalize

This should fix your stuck namespace.