Why do I need 'Ubuntu' and 'Advanced option for Ubuntu' and 'memory test' on grub?

Solution 1:

Why you have these options:
Ubuntu is hopefully the only thing you will have to boot into, but the others will become more useful if somethings breaks. For example, if the newest kernel has issues with your machine, then you can try booting with the old one under advanced options. Memtest is useful for looking for memory errors and stress-testing your RAM.

How to hide the other options:
I recommend using Grub Customizer to edit your grub options and instead of deleting the options having a menu folder labeled "other stuff" or something like that in case you need these in the future.

You can install Grub Customizer with these commands:

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer

Solution 2:

If Ubuntu is the only OS installed, you can hide this menu. Run

sudo -H gedit /etc/default/grub

and put # in front of GRUB_HIDDEN_TIMEOUT. Save the file and run

sudo update-grub

This menu can be useful if your system does not boot for some reason. But you can always get into it by pressing Shift, or ESC on boot.