We can turn off Config for a region and make it look it we never used Config for that particular region by using the following method
1) Turn off Recording for that region using the console
2) Delete the Rule by going to actions, delete rule
3) Use the AWS CLI and delete the default recording by ::
aws configservice delete-configuration-recorder –configuration-recorder-name default
4) Delete the service linked role created for AWS Config
Refresh the Config home page to make it appear fresh.
If necessary delete the config bucket and its objects.