You can also unfollow teams from within the app using the directions below.
Fans, Family, & Players
1) Go to the Feed of the team in question
2) Tap the blue box that shows your status on the team (Fan, Family, Player)
3) Confirm that you would like to unfollow the team
1) Go to the Feed of the team you want removed
2) Tap the gear icon to go to the Team Settings
3) Scroll to the bottom of the settings, and tap the red Unfollow Team button (this will not be available if you are the lone Admin on the team)