How do I remove “Ubuntu” in the bios boot menu? (UEFI)

sudo apt-get install efibootmgr

sudo modprobe efivars

Then run sudo efibootmgr to check your boot entries

ex)

BootCurrent: 0004
Timeout: 2 seconds
BootOrder: 2001,0003,0005,0006,0000
Boot0000* Lenovo Recovery System
Boot0001* EFI Network 0 for IPv6 (B8-88-E3-84-F3-EF)
Boot0002* EFI Network 0 for IPv4 (B8-88-E3-84-F3-EF)
Boot0003* Windows Boot Manager
Boot0004* EFI USB Device (SanDisk)
Boot0005* ubuntu
Boot2001* EFI USB Device

sudo efibootmgr -b 5 -B 

https://askubuntu.com/questions/63610/how-do-i-remove-ubuntu-in-the-bios-boot-menu-uefi