You can use Grub Customizer or edit grub manually to disable grub menu from showing up and make Ubuntu default choice. That way you will no longer face a choice again and will directly boot to Ubuntu. I don't think you will want to really "remove" grub because you cannot boot Ubuntu without it.
If Ubuntu is the first choice in grub menu, while editing grub manually just changing GRUB_TIMEOUT=10
to GRUB_TIMEOUT=0
should be enough.
So,
- start Terminal and type
gksudo gedit /etc/default/grub
- change timeout to 0 in opening text editor
- type
sudo update-grub
you should be done.
If Ubuntu is not appearing as first choice in your grub menu, you also need to change that.