The /boot/grub folder is needed! What may be redundant (i am not sure) might be the grub subfolder under EFI. My guess is it is a remnant of another previously installed linux distro.
BTW at least by me, i tried deleting an old ubuntu boot entry with efibootmgr and is was recreated from the firmware on reboot. I had to mount the EFI partition and delete the ubuntu subfolder, then the boot entry was removed automatically without the need of efibootmgr commands.
p.s. if you decide to play with the efi partition (i am not responsible if you break your system)
open gparted and see which one it is, mine was nvme0n1p1
sudo mount -t vfat /dev/nvme0n1p1 ~/myefi
open thunar (maybe with root) and do what you want to do, like backing up and deleting
For reference, here is how mine looks - manjaro, Win11, and insyde is i do not know what, i guess firmware update tool from lenovo. Ubuntu is alredy deleted, so the other boot entry should also be manufacturer related like memtest or something.