efibootmgr # to see all boot options and their numbers
sudo efibootmgr -b <number> -B # to delete <number> boot
When you install a new OS, it may add a new boot option to the BIOS list. However, if you delete the OS without deleting the boot option, it will still be there. This is not a problem, but it can be annoying to see it in the list.
To delete a boot option, you need to know its number. You can see all boot options and their numbers with efibootmgr:
efibootmgr
Then you can delete the boot option with efibootmgr:
sudo efibootmgr -b <number> -B
Replace <number> with the number of the boot option you want to delete.