Disable CNAME check for all azure subscription

Disable

az feature register --namespace Microsoft.Network --name BypassCnameCheckForCustomDomainDeletion

Enable

az feature unregister --namespace Microsoft.Network --name BypassCnameCheckForCustomDomainDeletion

Check the status

az feature list -o table --query "[?contains(name, 'Microsoft.Network/BypassCnameCheckForCustomDomainDeletion')].{Name:name,State:properties.state}"