If the source of an inbound security group rule or destination of an outbound security group rule needs to be changed, you need to first delete the security group rule and add a new one.
Security group rules use whitelists. Deleting a security group rule may result in ECS access failures.
Deleting multiple security group rules at once
You can also select multiple security group rules and click Delete above the security group rule list to delete multiple rules at a time.