Make changes to WordPress Media Settings and make sure the following setting under Uploading Files is unchecked.
- Organize my uploads into month and year-based folders
WordPress always organises media files into month and year based folders by default. You don't want this. So make sure that box is unchecked.
Date based folders are generally undesirable as your photos could end up in scores of separate folders. Some of these will be empty if you do not post regularly. This means, you create longer, pointless file specifications for each of your images.