Documentation for deleting files (improvement) (#791)

* improved JS doc for deleting file

* removed required reference to delete file

* changed bullet point to headline

Author: mtrezza

_includes/js/files.md

@@ -113,20 +113,17 @@ Parse.Cloud.httpRequest({ url: profilePhoto.url() }).then(function(response) {
 
 ## Deleting Files
 
-You can delete files that are referenced by objects using the [REST API]({{ site.baseUrl }}/rest/guide/#deleting-files). You will need to provide the master key in order to be allowed to delete a file.
-
-If your files are not referenced by any object in your app, it is not possible to delete them through the REST API.
-
-Alternatively, starting with Parse Server 4.2.0, you can delete files using cloud code.
+You can delete files that are referenced by objects using the `destroy` method. The master key is required to delete a file.
 
 ```javascript
-Parse.Cloud.beforeDelete('Profile', async (req) => {
-  const profile = req.object;
-  const profilePhoto = profile.get("photoFile");
-  await profilePhoto.destroy({ useMasterKey: true })
-});
+const profilePhoto = profile.get("photoFile");
+await profilePhoto.destroy({ useMasterKey: true });
 ```
 
+#### Parse Server <4.2.0
+
+Use the [REST API]({{ site.baseUrl }}/rest/guide/#deleting-files) to delete a file.
+
 ## Adding Metadata and Tags
 
 Adding Metadata and Tags to your files allows you to add additional bits of data to the files that are stored within your storage solution (i.e AWS S3).