Never occured to me that you can do this.
But have now seen a couple of how to videos (on youtube!) and it seems to be fairly simple.
Go to apps ie links to streaming services.
Hold remote button down while on the YouTube app and a menu should appear with an option to delete.
See this video (sorry you will need youtube to watch it!)
Another video says if you dont get the menu with the option to delete go to the youtube app and click on the info butten which brings up another menu that also has the delete option.
Hope this helps.
And if it works can you post about how easy it was to do?