How to list all App Services within an App Service plan using PowerShell
Here is the PowerShell command to list out all the App Services running on an App Service Plan.
$asp=Get-AzureRmAppServicePlan -ResourceGroupName "<RGNAME>" -Name "<ASPNAME<"
$apps=Get-AzureRmWebApp -AppServicePlan $asp
Foreach($app in $apps) { $app.Name }