That's GNU GRUB, version 1.xx or greater, also known as GRUB 2. With a traditional BIOS-based boot, it lives in the Master Boot Record and in the normally-unused sectors located after the MBR but before the beginning of the first partition. It also typically has its configuration file and some modules available as files within one of your disk partitions, but these parts can optionally be embedded within those disk sectors.
The instructions provided by user345866 would be applicable for configuring GRUB from within a Linux OS, but apparently you don't have one. The fact that your bootloader includes a
(No SLIC) option makes me think your version of Windows might be a pirated one.
SLIC is the older version of a BIOS-embedded Windows license, and it turned out to be duplicateable and "transplantable" to other systems. Your bootloader might be something like that. The modern version is
MSDM: it is tied to the specific system the license is issued for, using pretty strong cryptography.)
In that case, the GRUB bootloader might be used as a delivery mechanism for the tools used to bypass the Windows licensing check, and its configuration might be entirely embedded within those normally-unused disk sectors between the MBR and the beginning of the first partition. If so, then the GRUB configuration cannot be changed without having the tools and configuration files that were originally used to "package" that particular installation of GRUB. So unless you find a
grub.cfg file on one of your disk partitions, you might be out of luck.