How to unalias the default Firebase project?

Question

After unaliasing my "default" project, Firebase still uses it:

> firebase use --unalias default
Removed alias default

Run firebase use --add to define a new project alias.

> firebase deploy

=== Deploying to 'myproject0'...

My code base is deployed on multiple projects that I use as separate environments. I would like to explicitly specify the project for all my Firebase CLI commands to avoid messing with production or staging environments.
Is it not possible to unalias the default project?
Am I doing it wrong?

My .firebaserc is successfully updated:

{
  "projects": {
    "production": "myproject0",
    "test": "myproject-test"
  },
  "targets": {
    "myproject0": {
      "hosting": {
        "superadmin-webapp": [
          "superadmin-myproject0"
        ],
        "client-webapp": [
          "myproject"
        ]
      }
    }
  }
}