The TouchWiz is the default launcher on Samsung Galaxy S7 and S7 Edge. To change the default TouchWiz launcher and switch between launchers on Galaxy S7 and S7 Edge, do as follows:
1. Open the Settings app on your S7
2. Go to the Applications settings, under the Phone settings
3. Now touch the Default Applications option
4. Tap the Home Screen option to specify the default launcher when going to the home screen
5. Now, the list of default launchers (TouchWiz and TouchWiz Easy) and the already installed 3ed party launchers (Nova Launcher, APEX...) is shown
6. Select the new launcher you want to switch to, and then press the Home Button to apply this new launcher to the home screen and your device.