I think I found a workaround for this issue of not being able to customize the antenna and streaming channels of the free TV on Roku.
The trick is to go into the guide while you’re watching live TV by pressing the left arrow.
Then scroll down and select (watch) each of the channels that you want to keep (going back to the guide each time) and once you made it through the entire guide, press the star options button and choose the option to show “recent channels” instead of “all channels” and that at least will only show you the channels that you watched. I’m not sure how many channels are kept in “recent” and it looks like it doesn’t remember by channel order but at least it’s something.
Be very careful not to watch channels you don’t want to show up.
It is not a perfect solution by any means and a very annoying design flaw. I’m sure it’s not a ROKU issue as much as a TCL issue as we had no trouble selecting and hiding channels on our previous ROKU TV by Hitachi which has better options for live TV as does Vizio, Samsung and many others. Honestly this lack of customization is a reason I will not buy another TCL Roku.