I wouldn't bother.
1. From what I've heard playing WGT on FB can lead to quite a few problems with game play and other errors, just play it direct from WGT's site.
2. Even when you opt out you get hundreds of emails from WGT about competitions you've entered that are changing, stuff you've purchased etc.
Me personally, I deliberately set up a secondary email address that WGT can dump all their rubbish to without bothering me at my main account.