Well I've done a bit of googling on this. I have found that the option to remove titles, ie demos or free tiles from the library has been asked for years. The earliest request I found was from 2017. So I believe the just don't want to let us. I guess it's a numbers game, you see if you keep accidentally keep installing the title, it looks like it's been downloaded many times.
If anyone else has ideas why they keep refusing to add this function please comment.
To me is an easy addition. Don't even have to change any firmware. Just give me a webpage I can do it on.