How to stop a service?

You cannot stop an AWS Service, you can use those services. if you want to stop usage (i mean billing also) . you need to remove all resources that are using the relevant service.

As an example

Amazon EC2: To stop an Amazon EC2 instance:

Sign in to the AWS Management Console. In the navigation pane, choose 'Instances'. Select the instance you want to stop. Choose 'Actions', then 'Instance State', and then 'Stop'. When prompted for confirmation, choose 'Yes, Stop'. Note: Stopping an instance doesn't delete your data. However, any data stored in the RAM of the instance is not saved.

AWS Data Transfer: Data Transfer in AWS usually refers to the data going in and out of AWS services like Amazon S3, Amazon EC2, and others. To stop or reduce AWS Data Transfer, you need to stop or reduce the services that are causing the data transfer. This typically means stopping EC2 instances, terminating load balancers, reducing S3 usage, etc.

Remember that if you stop using a service, you might want to consider deleting or terminating the resources associated with that service to avoid incurring unnecessary costs. Also, AWS free tier has a limit on usage, so even if you're within the free tier, if your usage exceeds the limit, you may be charged.

If you need further details please elaborate on the problem in more detail.

There is no concept for stopping a service, there is no need to do that. The free tier menu just indicates what's available. As long as there are no resources created in your account relating to these services you won't get charged any of these services.

Check the following article to avoid any unexpected charges after the free tier (Avoiding unexpected charges after the AWS Free Tier) -> https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/billing-free-tier.html