As you know, there is a built-in web interface which is basically a simple web app. You can use it when you are at home, or use it remotely if you set up port forwarding. The point of Blynk is that it provides cloud service so that you can access the device remotely without setting up port forwarding.
You can customize the Blynk app by first stopping it (clicking the stop icon), then click on widgets that you don’t want and delete them. For example, the LCD widget may be confusing so you can just delete it.