There are a few ways to remove the GRUB bootloader from BIOS. One way is to use the Bootrec.exe tool in the Windows Recovery Environment. To do this, firstly boot into Windows Recovery Environment by pressing F8 during startup. Once in the Windows Recovery Environment, go to the Command Prompt and type in "Bootrec.exe /FixMbr" without the quotes. This will remove the GRUB bootloader from BIOS and should allow you to boot into Windows normally.
Another way to remove the GRUB bootloader is to use a Linux live CD/USB. Once you have booted into the live environment, mount your Linux partition and then delete the GRUB files from the /boot/grub directory. This will remove the GRUB bootloader from BIOS and should allow you to boot into Windows normally.
yet another way, which is more permanent, is to reinstall Windows. This will overwrite the MBR and remove the GRUB bootloader from BIOS. However, this will also delete any files and data on your Windows partition, so make sure to backup any important data before proceeding.