Deleting an Amazon EBS Snapshot
When you delete a snapshot, only the data exclusive to that snapshot is removed. Deleting previous snapshots of a volume does not affect your ability to restore volumes from later snapshots of that volume.
If you make periodic snapshots of a volume, the snapshots are incremental so that only the blocks on the device that have changed since your last snapshot are saved in the new snapshot. Even though snapshots are saved incrementally, the snapshot deletion process is designed so that you need to retain only the most recent snapshot in order to restore the volume.
Note that you can't delete a snapshot of the root device of an EBS volume used by a registered AMI. You must first deregister the AMI before you can delete the snapshot. For more information, see Deregistering Your AMI.
To delete a snapshot using the console
Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.
Choose Snapshots in the navigation pane.
Select a snapshot and then choose Delete from the Actions list.
Choose Yes, Delete.