You could theoretically remove them with ADB commands, but you would first need to setup wireless ADB (or a keyboard, I suppose) and determine the package names.
I don't think you can remove those, the user doesn't have much control on the UI and content with Google TV.
Don't know if it works on your set however...on my Bravia I press the Input button. I move through all the Inputs available which include my featured apps such as Netflix and Apple TV. When I get to the end of the list there is a edit option. This lets me turn any inputs and featured apps on or off.
But if you get rid of 9Now how will you watch MAFS? /s
You can't.
Enjoy your how Chromecast with Google TV
You can't press and hold the center button? I can with the apps preinstalled with my Google TV / Android TV 10...