Every workspace is linked to a single FireCloud Billing Project that tracks all cloud storage and cloud compute costs incurred within that workspace. You can create FireCloud Billing Projects if you have access to a Google Billing Account and give others permission to use it.
The FireCloud team owns and administers the FireCloud projects billing expenses to their credit card. They don’t have owner privileges. They can see billing activity in the console but that’s about it. If you as a user of FireCloud have a billing account and want full ownership, you can create regular GCP (Google Cloud Platform) projects that you wholly own, pay for, and can do what you want with.