You cannot totally remove your data from their system, so you’d better use the tip below and anonymise your data.
Then, send an email to NFLPrivacy@nfl.com to request cancelling of your account.
See http://www.nfl.com/help/privacy#data for more information.
URLS:
http://nfl.com
they have serious spam or list buying issues. I’ve had accounts created with 2 of my email addresses, and they send unsolicited email. even choosing to ignore the nfl they’ve still managed to invade my living room.