How to enable TLS for openfaas 1 click app

Hi guys. I installed the OpenFAAS one click app from here: https://marketplace.digitalocean.com/apps/openfaas-kubernetes

I would now like to enable TLS and have followed the linked instructions here:

https://docs.openfaas.com/reference/ssl/kubernetes-with-cert-manager/#20-ssl-and-custom-domains-for-functions

This command fails:

helm upgrade openfaas \
    --namespace openfaas \
    --reuse-values \
    --values tls.yaml \
    openfaas/openfaas

With

Error: UPGRADE FAILED: "openfaas" has no deployed releases

It doesn’t look like the digital ocean one click installer has created a deployment or any releases. Can I modify this command to still use helm values file to create the ingress?

I realise I could make the ingress myself, but would prefer to stick to the official helm chart.

Failing that, how do I uninstall the one click app? And I can start again by using the helm chart instead.

Many thanks,

Gavin