Before starting, make sure that your windows drive (NTFS) is mounted in RHEL system. Otherwise, you won’t see windows OS in steps following below.
To mount Windows NTFS drive, please check this quick tutorial post for RHEL 7.
Check that windows is detected. Run following command:
If Windows was listed anywhere, let’s save the new configuration file by first making a backup first, just in case.
sudo cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.old
save the config file:
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
Reboot your system, now you must see Windows option in boot menu.