There are a couple of ways to accomplish this:
- Right-click on the game tile
- Click on the small white arrow in the bottom-right corner of the game tile
You may then select Hide from the menu. This will not remove the game from your account, it will only change the display location in Uplay.
Collapsing the various categories will bring you to the Hidden section. Here, all hidden games can be found from your games library.
If you wish to reverse the process, navigate to the Hidden games section, find the game you want to be included in your library again, and right-click on the game tile, or select the arrow once more. Choose Unhide from the menu.