Click the Unsubscribe tab on the Email & Alerts page of any organization's Rainout Line page, or Unsubscribe here
Follow the steps on the page.
You will be sent a verification code to your device to verify someone is not trying to unsubscribe you without your approval. You must enter this verification code into the website for your changes to be made.
The next page will allow you to select which alerts to cancel, you may selectively choose to keep some or remove them all by clicking the check boxes and pressing the "Verify" button to make your changes final.