After you create an App Engine application, the App Engine default service account is created and used as the identity of your App Engine app. The App Engine default service account is associated with your Cloud project and executes tasks on behalf of your apps running in App Engine.
By default, the App Engine default service account has the Editor role in the project. This means that any user account with sufficient permissions to deploy changes to the Cloud project can also run code with read/write access to all resources within that project.
You can change the permissions for your service accounts in Cloud console. For example, you can downgrade the permissions used by the App Engine default service account by changing its role from Editor to whichever role(s) that best represent the access needs for your App Engine application.
To change the permissions for your service accounts:
Open the Cloud console:
In the Principals list, locate the ID of the App Engine default service account.
The App Engine default service account uses the ID:
You can then use the dropdown menu to modify the roles assigned to the service account.
Using the default service account
Your App Engine app uses the credentials of the App Engine service account by default. For more information, see Granting your app access to Cloud services.
If you delete your App Engine default service account, your App Engine application might break and lose access to other Google Cloud services, such as Datastore.
You can restore App Engine default service accounts that have been deleted within the last 30 days by following the steps in undeleting a service account.