To delete your UG account:
Open the Tabs app.
Navigate to Profile.
Go to Settings.
Tap Delete account.
Accounts registered with Google, Facebook, or Apple
If your UG account is attached to your Facebook or Google profile, you'll get a deletion link on your Facebook or Google email address.
Note: Auto-renew for your web or Android subscriptions will be canceled when you delete your account but your iTunes subscription will stay active.
You should cancel your iTunes subscription through your Apple ID using this instruction.