On a used computer that has the original users name on everything, I remember there is a way to change directories etc.  
I know changing the computer owner name in the registry key HKEY_LOCAL_MACHINE, Software,Microsoft,Windows NT, CurrentVersion,RegisteredOwner.
However that doesn't change the name in USER.  
I've done this years ago but I can't remember now.  Normally nobody cares or does this anymore.  But I have one I want to change now.
It came with Microsoft Office and they don't want to lose that.  And they've been using it for a while so it has some other software installed along with pictures etc.