WAF Cost per day $0.27 since 16/05/2023, unable to determine from where the cost is incurred

The first step is to identify the region where the WAF and Web ACL rules are located.
Check your invoice or Cost explorer to see in which region you are charged.
Once the region is identified, change to the region with Web ACLs, etc., and follow the procedures in the following document to remove them.
https://docs.aws.amazon.com/waf/latest/developerguide/web-acl-deleting.html

For fee waivers, please open an "Account and billing" case with AWS Support.
However, please note that this is not a guarantee of waiver.
https://docs.aws.amazon.com/awssupport/latest/user/case-management.html

Hi,

Thanks a lot for your prompt response! I was able to delete the web ACL rule after knowing it is under Global region. The "region" option in WAF can be easily overlooked.

Can you please let me know how WAF was used in this scenario, where the CloudFront service was deleted long time ago? Does that mean even if CloudFront is deleted, the attached web ACls continues working? For what purpose?

Regards, Joyce

CloudFront and AWS WAF are two different services, so even if CloudFront was deleted, AWS WAF would have remained unerased.
AWS WAF is not used if not tied to a resource.
Note, however, that a fee will be charged while it remains as a resource.

Thanks for the insights. That explains :).

Regards, Joyce