In order to uninstall google messages app, set the stock message app as default. Open playstore and search google messages. Click on it then click uninstall. If its the stock app you no longer want, you cant uninstall it but, hold the app then click i, at the bottom tap disable.
It's not only message apps, but several other apps are duplicates as well. Samsung needs to give option to let us choose between which apps to keep in the beginning and other to get rid off.
