Remove grub boot sector from a partition

I accidentally installed grub boot sector onto partition /dev/sdc1 instead of /dev/sdc, which is wrong. To remove the boot sector from partition /dev/sdc1:

sudo dd if=/dev/sdc1 of=sdc1.bootsector bs=512 count=1
sduo dd if=/dev/zero of=/dev/sdc1 bs=512 count=1

The file sdc1.bootsector is a backup in case anything go wrong.