How do you get rid of a dual boot?

[Amazin Caucasian]

Long story but i accidentally ended up with a dual boot on one of my dad's computers...now everytime it boots up you have to choose which Windows you want. My dad has been on my case for a while now about getting that off, i told him all he has to do is select the certain windows but he refuses and insists upon me ridding of the dual boot for his ease...Now I was wondering how i can get rid of that second not working copy of Windows on that computer?

My story, i tried to reinstall XP on my computer but for some reason it wasnt working...so i tried to install it by putting my hard drive in my dads comp and using my disc and it worked...little did i know, the novice i am, that it codes the copy to that mobo...now i know but i got my situation worked out but elft my dads computer with a dual boot of XP one being the copy i had installed to my hard drive which is no longer in there.

[ktkendall]

edit the boot.ini file which is in the root directory of C:, and just remove the line that has the unwanted OS choice. You may want to back that file up first if you aren't sure what you are doing though.