Cancel a phone number
You can unsubscribe a phone number whenever you want. There will not be any additional renewal charges thereafter.
To unsubscribe a phone number, sign into the web app and go to the Phone numbers page.
Click on the number you want to unsubscribe, and then select Number details in the right window.
Click on Change and then scroll down and select the option Do not renew and then select Done.
The number will now be removed automatically from your account at the next renewal date.
Here is a video that shows how to cancel a phone number.