Completes the asynchronous operation started in BeginDeleteFile.
true if file was deleted successfully.
Before calling BeginDeleteFile, you need to create a callback method that implements the AsyncCallback delegate. This callback method executes in a separate thread and is called by the system after BeginDeleteFile returns. The callback method must accept the IAsyncResult returned by the BeginDeleteFile method as a parameter. This parameter may then be passed to the EndDeleteFile method to complete the operation.