Hi Karthic Ganesan,
Did you try deleting the v-net, subnet and container app using terraform destroy command?
Also, can you use below cli command:
You can first delete the Service Association links on the V-Net by using this command:
Azure CLI
az rest --method delete --uri https://management.azure.com/subscriptions/<subscription id>/resourceGroups/<resource group>/providers/Microsoft.Network/virtualNetworks/<vnet name>/subnets/<subnet name>/providers/Microsoft.ContainerInstance/serviceAssociationLinks/default?api-version=2018-10-01
And then remove subnet-delegation by using the command below:
Azure CLI
az network vnet subnet update --resource-group <resource group name> --name <subnet name> --vnet-name <vnet name> --remove delegations
Ref: https://sathyasays.com/2021/06/05/delete-azure-vnet-subnet-delegation/
After the associations and delegations are removed, Retry the deletion of the V-NET and container app.