Hi @Anonymous User
No problem removing the YouTube App on my NOW Stick by going into the My Apps section, highlight the YouTube App, then press the star button on the remote to remove the App.
Running the same software version 9.4.3 build 4094-56 on the NOW Stick.
Please note, that you can remove Apps from the My Apps section, but unfortunately the NOW hardware / software doesn't allow you to lock Apps for future access.
So for example Kids can still go to the Apps Store on the Stick and re-add the Apps again that you don't want them to use (customers have been asking NOW for years on a method to block Apps or add a security access PIN on them so you can control who has access to these Apps on the NOW branded devices in your home).