In order to leave your League, tap on the League icon at the bottom of the screen, then open the "Members" tab and press the red "X" next to your name. A screen will then appear prompting you to confirm that you want to leave this League.
In order to leave your League, tap on the League icon at the bottom of the screen, then open the "Members" tab and press the red "X" next to your name. A screen will then appear prompting you to confirm that you want to leave this League.