...Use os-prober-efi -h for more informations!
30_os_prober_efi ist the grub-mkconfig script (update-grub) and generates for each entry (*.efi) found in /boot/efi/EFI/... a menuentry.
You can disable them in "/etc/default/grub".
NOTE: /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi is the regular EFI-Loader for Windows!
Possible Variables (optional) - they need export and must be stored in "/etc/default/grub":
export GRUB_DISABLE_OS_PROBER_EFI=true
-- Disable the script 30_os_prober_efi
export GRUB_DISABLE_EFI_directory_loader=true
-- Disable directory and/or loader (first found=disabled)
Example for disable the loader /EFI/Microsoft/Boot/bootmgr.efi:
export GRUB_DISABLE_EFI_MICROSOFT_BOOT_BOOTMGR.EFI=true
Example for disable the complete folder boot/efi/EFI/grub:
export GRUB_DISABLE_EFI_GRUB=true
Startup Manager is a program that provides you the possibility to manage the Windows startup procedure. It offers you the possibility to control which programs automatically start up and more.