You can customize your guide completely, changing the order of the channels and even hiding them. To do so, in a web browser, go to tv.youtube.com and login. Then click your profile picture in the upper right corner, and click Settings, then Live Guide.
You can drag and drop your favorite channels to any order you wish.
Then, on any devices you're watching, just make sure your custom list is selected. On a TV, you'll see an icon in the Live screen with three lines, right above the start of the guide listing. Click that and you'll be able to choose Custom.
On mobile or a computer, you'll see a Sort option above the live guide, that will let you choose your custom guide.