you cant uninstall windows 8. In order to get windows 7 , you must have a clean install of windows 7 again. It may be frustrating but no other way. I also didn't like windows 8.
In his case, he doesn't necessarily need a clean install of Win 7. All he needs is a system image of his Win 7 installation (with the then installed software and all), use his Win 7 system repair disk and try to restore the old system image, which process will first come up with an error message saying that boot repair is required. After boot repair, he would be able to recover his system back to the condition it was in just before installing Win 8 over Win 7 ("Upgrade Mode"). This is exactly what I did successfully after I was similarly dissatisfied with Win 8 CP. In fact, there was a clear warning to this effect on the relevant Microsoft web page.
In my case, I have OS on Drive C and all application software on Drive D, both of which together formed my system image.
Of course, if someone doesn't have a system image, he/she has to start again from a scratch, which would be a pain.