How to delete a file using Cloud Functions?

For anyone else still head-scratching, I was able to get mine deleted by excluding the bucket name (and hence selecting the default firebase bucket):

 const bucket = admin.storage().bucket();
 const path = "path/to/file.wav";
 return bucket.file(path).delete();

take a look at this functions I have used

const app = admin.initializeApp();

export const onDeleteItem = 
 functions.firestore.document('collectionItems/{collectionID}/items/{itemID}')
   .onDelete((snap, context) => {
     const { collectionID } = context.params;
     const { itemID } = context.params
     return deleteItemImage(collectionID, itemID)
     }
 )

async function deleteItemImage(collectionID: string, itemID: string) {
  const path = `images/${collectionID}/${itemID}`;
  const bucket = app.storage().bucket();
  return bucket.file(path).delete()
    .then(function () {
      console.log(`File deleted successfully in path: ${path}`)
    })
    .catch(function (error) {
      console.log(`File NOT deleted: ${path}`)
    })
}

You can use the firebase functions environment config to get the bucket name:

const bucket = gcs.bucket(functions.config().firebase.storageBucket)

As far as I'm aware, it is not possible to delete firebase storage files from within cloud functions. You can listen to change events on a storage bucket, but you can't interact with it.

The way that I managed this was to remove the 'post' from the database using .set(null). This returns a promise which, when it resolves, you can use to make a delete call to firebase storage.

firebase.database().ref('Posts/{pushId}').set(null).then(() => {
  console.log('Post deleted from database')
  firebase.storage().ref(`Posts/${pushId}thumbnail-image.jpg`).delete().then(() => {
    console.log('Successfully deleted thumbnail');
  }).catch(err => {
    console.log(err);
  });
}).catch(err => {
  console.log(err);
});

Firebase storage won't allow you to recursively delete an entire bucket, so you need to delete each file one-by-one.