AB#6000: Retire one article for Azure Batch

Author: AmandaAZ

support/azure/hpc/batch/error-accountencryptionkeyunavailable.md

@@ -2,8 +2,6 @@
   href: welcome-hpc-batch.yml
 - name: Access to storage account is denied
   href: access-denied-execute-azure-batch-job.md
-- name: AccountEncryptionKeyUnavailable error message
-  href: error-accountencryptionkeyunavailable.md
 - name: Batch node creation delays when restarting or reimaging
   href: batch-node-creation-delay-restart-reimage.md
 - name: Batch node is stuck in Unusable state