I signed up for Firebase to use the new Firestore.
After trying it out I decided that, for my use cases (mostly server tools) I don't need most of the features of Firestore, that are very much focused on building user interfaces, and I find the old Datastore SDKs nicer for what I'm doing.
I know I could simply delete the project and create a new one but I have other things in that project that I would like to keep.
Can I revert to Datastore without starting a new project?
Unfortunately just as we cannot convert a project that has used Cloud Datastore to Cloud Firestore, we cannot do the reverse either. It might be possible in the future, but definitely not this year.
As noted, the renaming 2 options are: 1) Delete the project and create a new one with Cloud Datastore 2) Create a new project and talk to that projects database. Note: This won't work if you are using GAE Standard SDKs.
来源：https://stackoverflow.com/questions/48689605/revert-from-google-cloud-firestore-to-datastore