boot windows, go to c:\windows\system32\sysprep\sysprep.exe, select audit mode and reboot, click ok, when system reboots itself don't touch sysprep but instead open start menu, type in 'user profiles' and press enter
in that window delete your account which causes the problems, confirm by pressing ok, now in sysprep set OOBE and reboot, check generalize, confirm (might take a while)
incase it gives you error, you just have to kill wmpnetwk.exe process in task manager (it's known to cause issues with sysprep)
on next reboot your windows will be basically clean as if you just installed em (all your apps, drivers, games etc. will be there too so don't worry; it just gets rid of all the windows user account data - make SURE you backup all your stuff from desktop/documents/downloads etc folders before doing anything with sysprep, basically everything in c:\users\problematicaccount folder)
you just have to input typical stuff (location, user name etc.) afterwards