It usually won't allow you to remove a channel if you have an active subscription through Roku. Check at https://my.roku.com/account/subscriptions . Is it possible that you have a subscription through Disney as well as through Roku?
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution." If you appreciate my answer, maybe give me a Kudo.
For more information about that channel's authentication and functionality, you'll want to contact Disney + support directly to inquire further. Many channels on Roku are developed and maintained by the channel provider themselves.