About Operating System

I have the OS Windows98 in my computer. I had installed WindowsXP Professional Edition in my computer in another partition. But due to some problems I uninstalled that. Again I have installed WindowsXP in different partition. But the problem is that at the beginning when the OS choices menu comes there are two choices of WindowsXP and one for Windows98 appearing. One WindowsXP choice to go to the OS but the another WindowsXP choice is for the previous installation,which is totally useless. So, my question is how should I erease that choice?