Apologies! I understand it's a late response here.
To manage a public IP address on Azure Load Balancer, checkout the steps outlined in the doc: Manage a public IP address with a load balancer ( sections: "Create load balancer using existing public IP" and "Change or remove public IP address").
Troubleshoot Azure Load Balancer -This page provides troubleshooting information for Basic and Standard common Azure Load Balancer questions.