You can't. However, you can add a PIN to your account and those channels cannot be installed if you don't know the PIN. So while they can see the channel in the Channel Store, they can't install and use the channel.
Dan
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee, just another user.