AWS Billing Charges - How do I stop the particular service ??

Hello.

First, you need to find the public IPv4 in your account.
The AWS blog below describes how to search for public IPv4 in your account, so please follow these steps to search.
https://aws.amazon.com/jp/blogs/aws/new-aws-public-ipv4-address-charge-public-ip-insights/

If the public IPv4 can be identified and is no longer needed, billing should stop if you delete the AWS service that uses the public IPv4.