During the 30-day trial

You can cancel your account and delete your domain.

1. Sign in to the Google Admin console. 
2. Do one of the following:
   • In the classic Admin console, click Domain settings tab, then click either Subscriptions and billing or Billing information (depending on your billing system).
   • In the new Admin console, click Billing.
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3. Click the Cancel Google Apps for Business link.
4. Click Yes, cancel the free trial.

This change may take up to 30 minutes to take effect.

After the 30-day trial

If you have not entered your billing information and you do not explicitly cancel, your account will expire. However, if you've already entered your billing information, you should cancel to ensure that you're not charged at the end of your trial.

The first time that you sign in to the Admin console after your subscription has expired, you'll be prompted to either renew now or confirm your cancellation. If you don't renew or cancel, user access may be suspended.

If you would like to delete your account, please review this article on deleting Google Apps.