Install Nova Launcher and open the app drawer. Navigate to Nova Settings > App & widget drawers > Hide Apps. Select the apps you want to hide, and they won't show up on your app tray anymore. To reveal an app again, simply return to the same menu and uncheck the desired app.
Hanging problem ? I am not facing any such issues. Try to update it to lastest available OS update and check if you have installed any buggy app which runs in the background. I had installed some app in past from different website rather than playstore. After that I was facing slower performance but when I uninstalled it then it started working smooth again.
OnePlus 3T is better option. You are getting more powerful processor in less price and rest of the things are almost similar. Samsung C9 Pro has got bigger battery but Samsung always cost more than what it gives. Comparison
personally I like Apple IPhone 7 so would suggest for it ,is definitely a beauty worth beholding,owered by the most powerful processor so far and the latest iOS, the smartphone indeed solves your tasks in a jiffy. Apple IPhone 7 vs OnePlus 3T