I'm not using any resources in my AWS Free tier account, but still my free tier hours are being used daily.

Hello.
From the contents, it seems that ElastiCache's global datastore is activated.
If you do not need the resource, try removing it by following the instructions in the following document.
https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Redis-Global-Datastores-Console.html#Redis-Global-Datastores-Console-Delete-GlobalDatastore

If you cannot find the resource, try to find the active resource by following the procedure described in "Confirm that active resources are terminated" in the following document.
https://repost.aws/knowledge-center/check-for-active-resources

Hi Ram, The Global-NodeUsage:cache.t1.micro free tier is the sum of all your cache.t1.micro usage across all regions. If you have stopped/terminated your ElastiCache instances but your free tier usage is still increasing then it's likely you have instances running in another region. The second link Riku provided (https://repost.aws/knowledge-center/check-for-active-resources) should be helpful in identifying what's driving this. The billing console has changed slightly since that article was written, however. Look for the section entitled "Amazon Web Services, Inc. charges by service" and expand the "ElastiCache" section. That will break down your usage by region, which should help you determine where your running instances are located.

Check for ElastiCache across all Regions under Billing Dashboard->Free Tier. Take relevant action (remove/delete). Also check if there is any automation in place (e.g. CloudFormation) which is creating the cluster and consuming your free tier. https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/avoid-charges-after-free-tier.html