An HDInsight cluster is charged per hour of usage; hence, it is recommended that you delete your cluster if you are not using those resources. One great feature of Azure is that your data is still preserved on Azure Blob storage even after the cluster is deleted, and this storage can be used later to restore back your cluster. If you really want to delete all the data of your cluster, you need to delete the related Azure storage.
The following screenshot shows you the location of the DELETE icon for the cluster:
