BTW, what Maziye suggested
did not remove the games, it merely removed the menu so you don't see them. If someone wants to play them they can still find them and do so. If you want them removed you need to go to Control Panel\Programs and Features ... Turn Windows features On & Off & uncheck the Games option (first entry in the list) to remove Microsoft Games.
-AND-
Here is the WildTangent sites removal instructions; it clearly says at the bottom that WildTangent should be in control panel\Programs and Features so you can remove it (so if it is gone then something you did likely deleted it and you should try the other ideas on that page).
Then after that you might want to run the WildTangent Removal Tool from PCHell; it is at the bottom of the page
Here.