An internal error occurred while terminating the cluster. Contact Cloudera Support or log a support case. (TERMINATION_GENERAL_ERROR)
Instances may still be running when a cluster is in a failed state. You can choose to delete the cluster.
Hosted on Azure
You should first retry to terminate the cluster. We sometimes see Azure that fail the termination but where it succeeds on a second attempt.
If that doesn't work, we can dig deeper.