Many of the Subscription channels require you to cancel the subscription first before you can remove it from the Roku device. Head over to https://www.roku.com/ and sign in to your dashboard account and cancel the subscription under "Manage Subscriptions". Then try again to remove FTA Puerto Rico.
Generally, only the free channels/apps can be removed from the device simply using the * button. Or those in which you pay the provider directly.
If you have already canceled and still having trouble just removing the channel/app tile, go to Streaming Channels on the device home screen, search for the FTA channel/app, select it, and look for option "Remove Channel".
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102