This is actually very tricky to answer as it would depend on how you have structured the web app within Kentico as you may have modules that allow the addition of content within your web app (ie. the user doesn't need to go to the Kentico Backend). However, since the other thread you started is about staging, I would presume you will go that route and hence you should be able to use the IIS rewrite module on the live servers to stop all access to the '/Admin' sub-folder.
Note: the login page would still be accessible as it is in the CMSPages sub-folder. Hence you need to be aware about pages which have modules that users can use to add content.