[OriginalPainZ]

I usually use Microsoft DaRT (I have all ISO files for every Windows version and edition) to "reset" the Local Administrator Account password. It hasn't failed me to date.

"Bypassing" Is even better, particularly when using It on another system without It's user raising suspicion. You've mentioned It's not compatible on "some" Windows 8.1 OSes. What editions does this relate to? Also, Is It on both architectures?

I just try on Windows 7 (Pro and Family edition) it's Working, Windows 8 (Working), Windows 8.1 (Some not working I don't realy know why), Windows 10 (Working)
I like this tool because you can use it for "all" Windows OSes without channge your tool ISO and he can "bypass" passwords and you said it, it's better when you want to access a computer without permissions.