FileController.js

var Files = require('../services/FileService');

module.exports.deleteFile = function (req, res, next) {
    var query = {createdBy: req.user._id, key: req.params.key};
    var file = req.params._id;

    Files.remove(query, file, function (err) {
        if (err) return next(err);

        res.status(204).json({});
    })
};

FileService.js

var Uploads = require('../models/UploadService');

module.exports.remove = function (query, file, callback) {
    var update = {
        $pull: {
            files: {
                _id: file
            }
        }
    };
  
    // Calls the upload service to remove the file reference from db
    Uploads.update(query, update, callback);
};

routes.js

/**
 * routes.js
 *
 * @description :: Configure request router to appropriate Controllers
 * @docs        ::
 */

'use strict';

var express = require('express');
var router = express.Router();
var validate = require('express-jsonschema').validate;

var FileController = require('../src/main/api/controllers/FileController');

// Load Middleware libraries
var auth = require('../src/main/shared/middleware/authentication');

/**
 * Map HTTP Endpoints to controllers
 */
 
/**
 * Configure File Resources
 */

router
    .route('/api/file')
    .post(FileController.upload);

router
    .route('/api/file/:_id')
    .get(FileController.download)
    .delete(auth.isAuthenticated, FileController.deleteFile);

module.exports = router;