You are trying to remove Esxi from VDS but it says vmnic is in use and no VM's are there.

Products

• VMware vCenter Server
• VMware NSX

Issue/Introduction

When removing a host from the vDS, vCenter does a check to see if there are any resources still attached to it.  If resources are still using the vDS, the removal will fail..  Resources are virtual machines, snapshots of VMs, VM templates, vmnic or vmk interfaces. 

This article addresses the specific issue where NSX was removed in the past.  The removal either did not complete or it was done incorrectly.

Environment

VMware NSX
VMware ESXi

Cause

• When NSX is removed incorrectly, or the removal is not fully completed it will leave stale data associated with vDS.
• The vDS configurations are stored in the vCenter VCDB.
• When attempts are made to remove a host from the vDS the vCenter checks for resource attachments. 
• Improper removal of hosts or NSX can leave stale data in the vDS database entries.
• The stale data causes vCenter to register a resource that does not exist is still using the vDS.

This check is a guardrail intended to ensure virtual machines always have network connectivity.

Resolution

Workaround

• This is the cleanest and best option.
• Create a new vDS and migrate to it.
• This will address any stale data left from NSX.  Any future upgrade will not be hampered by any possibly missed stale data.

1. Create a vDS
2. Migrating from Standard to Distributed vSwitch

If a new VDS cannot be created, please open a case with Broadcom Support.