By delete do you mean going into the whole file system and just highlighting everything and deleting?
I'm dual booting with Win 7 RC but I didn't know that the options stay in your Boot Manager when you get rid of one OS . . . I would try doing a complete format of the drive that the OS was on so it's just empty space. Don't format your only OS though >.>
If you have Vista or Win 7 there's a formatting program in the Control Panel > Administrative Tools > Computer Manager > Disk Management. (Not sure if XP has one >.>) Just format the partitions that don't have your main OS on it and make sure you have all your info backed up. Formating will delete everything from the partition.
i totally reformated the partitions with the operating systems but the boot selector screen still has the os es my primary os is xp pro. when i select one of the deleted partitions it wont boot.......