I just removed windows from my laptop completely. I will install it on virtual box. My question is now, how and from where do I edit the boot options to boot directly in Ubuntu after I open my laptop without passing through the boot options page or if this is not possible, how do I remove the Windows boot line from there?
You can edit grub to don't wait any second (instead of 10 seconds) and boot the first option in the menu:
1) Alt + F2 and paste
2) Search for the line "GRUB_HIDDEN_TIMEOUT=10" and change it to "GRUB_HIDDEN_TIMEOUT=0"
3) Open a terminal and paste: