You may have to go into Folder Options in the control panel and unhide protected operating system files. You will want to find the Windows installation relating to the partition you want to remove. These will be in order of physical drives starting with 0 and then logical partitions. C = 1, D = 2 etc.

It will look something like this

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOW S
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windo ws Server 2003, Standard" /fastdetect
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Windo ws XP Professional" /fastdetect