If you need, besides major accounts, an extra account with limited access to data, you can add Windows 8 Guest account. The process is almost the same as in Windows 7.
There are some confusions about the features and and differences between the Windows 8 RT that came out with the Surface tablet and the "normal" version of Windows 8.
If for some reason your Android powered smartphone does not perform as good as it used to, or you want to sell it I suggest you to bring it to its original factory state.