nodejs create/delete local file on windows azure website "local storage"

I created a generic nodejs/expressjs app and git deployed to windows azure website (not web role, or virtual machine).

The folder structure is typical of an expressjs app:

app.js
package.json
routes/
public/
views/
node_modules/
temp_data/

The app can happily create and write files to the temp_data/ folder using nodejs fs.writeFile('temp_data\\temp_file',...,).

These can't be called "local storage", and not sure about the life time of these files. But as the names pointed out, they are temporary files.

The question is that when I tried to delete these files using nodejs fs.unlink('temp_data\\temp_file',...), after fs.exists('temp_data\\temp_file',...), it failed.

Is that because I have permission to write a file, but no permission to delete a file from a deployed folder?