How do I reset a deployments scale to use HPA after scaling down manually?

I have to turn off my service in production and turn it on again after a small period (doing a DB migration).

I know I can use kubectl scale deployment mydeployment --replicas=0. This services uses a HorizontalPodAutoscaler (HPA) so how would I go about reseting it to scale according to the HPA?

Thanks in advance :)