If you want to make your submissions private, you can go to your the settings tab of your profile, and scroll down to the box marked “set profile to private”. Here’s a video showing you how. This will allow only people logged into a Designlab account to view your profile and work:
We do not currently support an option to hide your submissions from other students. This is due to the collaborative nature of design – we've found that students tend to have the most success when learning with and from others, and we use the platform to help facilitate that.