Clear Google Play Failed Download Space
When we download big games (such as modern combat series), first play store download its additional files. Application/games additional files are saved on internal memory folder called "Android".  Inside of that folder, there's two directories. One is "data" other one is "obb". You can access that folder with any file manager app or by connecting your device to a PC (via USB or WIFI). (No need the root)

Search your app additional files in those folders and delete them. Most of the time additional files are saved with the app named folder. For an example "deadtrigger 2" game additional files saved folder called as "com.madfingergames.deadtrigger2".