how to remove public ip after migrating EC2 to IPv6 from IP v4

Hello.

If you follow the steps described in the answer at the URL below correctly, the public IPv4 will disappear from EC2.
https://repost.aws/questions/QUVmpO9BWGSuGwQh5tXk3f5w/how-to-remove-ipv4-public-ip-address-from-ec2-instances-before-february-2024-ipv6#ANIgCHiXgQSdSiHc1wgH-6fA

Indeed, even in my environment, I was able to confirm that public IPv4 was restored when I stopped and started EC2.
I think this is probably related to the "Auto-assign public IP" that was set when creating EC2, but as of March 2024, this setting is a setting that cannot be changed after EC2 is started.
Therefore, it may be best to operate EC2 without stopping it as much as possible.

Also, if you remove public IPv4, you will not be able to access external websites or applications that only support IPv4.
Public IPv4 is required for IPv4 communication.
Therefore, you will need to take measures such as NATing IPv6 to IPv4 using NAT64.
https://docs.aws.amazon.com/vpc/latest/userguide/nat-gateway-nat64-dns64.html