Hey @Birrael,
as far as I understand you want to know how to remove games from your list that you don't want anymore. Hope it's fine to answer you in English, as my Spanish is a bit rusty.
At the moment it's not possible to remove any games from your library or from the store that you don't want anymore. There is also no hide-option, so I guess best you can do here would be to leave feedback for the developers. You can simply tap your profile in the top right corner in the Stadia App or on stadia.google.com and press "feedback" to submit it.
