Cleaning up GRUB boot list the easy way

It used to be easy to edit grub to change your boot order, default OS etc. Then it got hard (too hard), and now it is easier than ever:

How do I change the grub boot order?

It is especially nice to be able to hide more comples options under a submenu e.g. Advanced settings. Note – you can’t indent an option but if you shift it up into a submenu it automatically indents.