Uninstall Extension with Firebase CLI

[rafaelvetronetrimb]

I'm trying to uninstall the extensions from my Firebase project using the CLI. I tried uninstalling them from the Console portal but I get a bunch of permission issues even though I have Editor and Firebase Admin roles.
I opened by firebase.json file and the extensions field is empty (I mean I did firebase init and selected an existing project, shouldn't it be created accordinly?).
Do I have to manually add the extensions in that file in order to uninstall the extension?