where was the grub installed? 1) if it was installed in mbr you can format MBR by DOS FDISK , by typing at the prompt the foll: C:>FIDSK /MBR
2) If grub was on the partition it must have been deleted, but still you can delete the partition and cat the free space to your partitions
Most important is that your active bootable partition should be set to the partition with windows installed on it.
Regards, Revant