How to clean up GRUB?

[gold_finger]

Open terminal and enter only these two again:

Code:

sudo apt-get update

Code:

sudo apt-get install grub-customizer

From your output in last post, after this:

Code:

sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
More info: https://launchpad.net/~danielrichter2007/+archive/grub-customizer
Press [ENTER] to continue or ctrl-c to cancel adding it

You were supposed to just hit enter to add the ppa.  It appears as though that is when you typed sudo apt-get update and then hit enter.  If that's what you did, then it probably just registered the "enter", but not the update command.  So, when you tried to install, the package lists were not updated to reflect the addition of the ppa source.  That's my guess at least based on what the output appears to show.