Changing config on Google Cloud K8s marketplace

I installed Gitea via the google marketplace which boots up a Kubernetes cluster, and the install went well.

However now I am attempting to change the config, specifically to disable new user registration, and I am wondering how this is done in this setup?

Hi, this product on GCP is maintained by Google Team. We will contact them.

Was there any word from the Google Team? Also perhaps there is something generic about K8s and their setup that I can borrow from?