How do I keep other member of my Google project from connecting to my NGC VM?

Google Cloud Platform projects allow any user of a project to access any virtual machine instance created within the project. This means that other users of the project in which you created an NGC VM could establish an SSH connection to your instance. To keep your VM instance private, create a new project only you have access to and then create and launch your NGC VM instances from within your private project. Read about creating and managing GCP projects here - https://cloud.google.com/resource-manager/docs/creating-managing-projects .