Powershell to dissociate nsg from subnet.

Question

Hi All:

I am running the Remove-AzNetworkSecurityGroup pwsh command to delete an NSG, this NSG is currently associated with a subnet but there is no direct access over portal to dissociate from the subnet via Azure portal, so the deletion is stuck.

Can anyone kindly provide a quick pwsh one-liner to dissociate NSG from subnet ?

Many Thanks

Answer 1

Hello @FATOBA, KIMBERLY ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that you are running the "Remove-AzNetworkSecurityGroup" PowerShell command to delete an NSG, but this NSG is currently associated with a subnet, and you don't have direct access to Azure portal to dissociate it from the subnet, so the deletion is stuck. You need the PowerShell command to dissociate NSG from subnet.

You can find the PowerShell commands for dissociating a network security group from a subnet in the below doc:

https://learn.microsoft.com/en-us/azure/virtual-network/manage-network-security-group?tabs=network-security-group-powershell#associate-or-dissociate-a-network-security-group-to-or-from-a-subnet

Instead of declaring the NSG, you can add $null to the Set-AzVirtualNetworkSubnetConfig command to disassociate the NSG as below:

## Place the virtual network configuration into a variable ##

$vnet = Get-AzVirtualNetwork -Name vnetname -ResourceGroupName rgname

## Update the subnet configuration to disassociate the NSG using $null ##

Set-AzVirtualNetworkSubnetConfig -Name subnetname -VirtualNetwork $vnet -AddressPrefix 10.0.0.0/24 -NetworkSecurityGroup $null

## Update the virtual network ##

Set-AzVirtualNetwork -VirtualNetwork $vnet

I tried it in my lab and it works as you can see from the below screenshot:

Then you can delete the NSG using the below command:

Remove-AzNetworkSecurityGroup -Name "nsgname" -ResourceGroupName "rgname"

Kindly let us know if the above helps or you need further assistance on this issue.

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Answer 2

Hi,

If you navigate to the NSG in the Azure portal, open Subnets blade, you can click on the context menu (three dots) to the right of the subnet and choose Disassociate.

Please click Accept Answer if the above was helpful.

Thanks.

-TP