First delete the StatefulSet. This will also terminates the pods. It may take some while.
kubectl delete statefulset mysql
Verify there are no pods running by following command.
kubectl get pods -l app=mysql
No resources found.
Delete ConfigMap, Service and PVC by following command.
kubectl delete configmap,service,pvc -l app=mysql
configmap "mysql-config" deleted
service "mysql" deleted
service "mysql-read" deleted
persistentvolumeclaim "data-mysql-0" deleted
persistentvolumeclaim "data-mysql-1" deleted
persistentvolumeclaim "data-mysql-2" deleted