Unrooting can be done in the same way you root. By patching an update file through recovery mode or via Odin.
Risks of rooting: https://www.google.co.in/search?q=risks+of+rooting . Mainly, destroys warranty of your phone and will have security risks if you install anything from a shady developer.
I appreciate your briefings . I have an unrooted device and I have installed an autocad software in it. Do you have a credit card ?
Credit card? Please don't hijack this thread. PM me if you need to ask me anything.
Credit card? For what? Doesn't seem to me as if he's only going to be hijacking this thread.