Hi there @nerraw14,
You may or may not be aware but Smartline is a fairly new product for GoDaddy and we are continually working on adding and enhancing features. Currently, the only way to change your SmartLine number is to cancel your current SmartLine account and start from scratch with a new number. Stay tuned for any additional changes!
At this time the only way to change your SmartLine number is to cancel your current account and start a new one with a new number. Our customer support team can help you do this. Give them a call at 480-505-8877.