Splat the wasp collects play games username and highest score and sends that off to a server for storage and retrieval. This data is ONLY collected in the case where the user signs into Google play games within the app.
This data is not processed or analysed on the server or sent to any 3rd parties. It is only used to store and retrieve information intend for the purposes of the leaderboard.
If you have connected to Google play games and no longer wish to send this data then clear the app cache and data which will require you to log in again before any such data can be sent.