+1 on what Golfdriver97 said.
Common misconception that goes around about KNOX security is that is can be easily removed or installed. If that was the case it wouldn't be as secure of a setup as Samsung has billed it to be and to meet the strict requirements of the business world. I'm sure there is options of rooting your device and flashing custom ROM (OS) builds but that isn't as easy as literally just going to the Google Play store and downloading and installing or uninstalling an app.