Deletion is definitely less common, but we do this all the time. It keeps cruft from accumulating when people forget to delete resources.

It's also nice to be able to do "helm del myapp" and know that everything is wiped. You can do this with "kubectl delete -R -f", but I believe you need the original files. You can of course do something like "kubectl delete -l app=myapp", but this requires consistent use of a common label in all your resources.