Thanks for asking question! You may want to know that Azure deploys each new App Service plan into a deployment unit, internally called a webspace.
Could you please double check if the resource group you created in 2nd step az group create -n app0 -l westus –debug
is in Free Sku or other?
Refer here for parameters of az group delete
For deleting App service plan you can use az appservice plan delete
Also note that It is not possible to delete an AppService plan
when it is associated with a WebApp
and if you want to delete both the webapp
and appservice plan
together you can use webapp delete
command.
Let us know.