This script will enumerate through a Storage Account and delete files that are older than x

Remove-AzureBlobStorage.ps1

#requires -version 2
<#
.SYNOPSIS
  This script will enumerate through a Storage Account and delete files that are older than x
.DESCRIPTION
  The script requires you to log into your account then automatically pulls your Account Keys.
  Using the Storage Account Keys, the script searches for files older than the provided date
.PARAMETER SubscriptionName
  Name of your Azure Subscription - Required
.PARAMETER ResourceGroup
  Name of the Resource Group that the Storage Account is in - Required
.PARAMETER StorageAccount
  Name of the Storage Account that the Container is in - Required
.PARAMETER Container
  Name of the Container holding the files/blobs - Required
.PARAMETER FileExtension
  File extension filter.  Script will search for files matching this extension
.PARAMETER DaysToKeep
  Delete files older than X days
.PARAMETER DryRun
  Switch param, if provided, do not delete, just log what would be deleted
.INPUTS
  None
.OUTPUTS
  Outputs to the console
.NOTES
  Version:        1.0
  Author:         Jeff Anderson
  Creation Date:  February 7th, 2018
  Purpose/Change: Initial script development
.EXAMPLE
  .\Remove-AzureBlobStorage.ps1 -SubscriptionName "Sub1" -ResourceGroup "SQLBackupsRG" -StorageAccount "Backups" -Container "SQLBackups" -FileExtension ".bak" -DaysToKeep 31
#>
param (
  [Parameter(Mandatory=$true)]
  [String] $SubscriptionName,
  [Parameter(Mandatory=$true)]  
  [String] $ResourceGroup,
  [Parameter(Mandatory=$true)]  
  [String] $StorageAccount,
  [Parameter(Mandatory=$true)]
  [String] $Container,
  [Parameter(Mandatory=$false)]
  [String] $FileExtension = "*",
  [Parameter(Mandatory=$true)]
  [int] $DaysToKeep,
  [Parameter(Mandatory=$false)]
  [switch] $DryRun
) 
function ValidateFileExtension {
  param (
    [Parameter(Mandatory=$true)]
    [String]$Extension
  )
  if ($Extension -eq "*") {
    return $Extension;
  } else {
    if ($Extension.StartsWith(".")) {
      return "*$Extension";
    } else {
      return "*.$Extension"
    }
  }
}
$Now = [DateTime]::Now
$Extension = ValidateFileExtension -Extension $FileExtension
## Authentication
Write-Output ""
Write-Output "----------------------- Starting Script ------------------------"
Write-Output "$Now"
Write-Output "Subscription Name: $SubscriptionName"
Write-Output "Resource Group: $ResourceGroup"
Write-Output "Storage Account: $StorageAccount"
Write-Output "Container: $Container"
Write-Output "File Extension: $Extension"
Write-Output "Days to Keep: $DaysToKeep"
if ($DryRun) {
    Write-Output "DRY RUN - NOT DELETING ANYTHING"
}
Write-Output "------------------------ Authentication ------------------------"
Write-Output "Logging in to Azure ..."
try {
  Login-AzureRmAccount
  Select-AzureRmSubscription -SubscriptionName $SubscriptionName
} catch {
  Write-Error $_.Exception
  exit
}
## End of authentication

## Get Storage Account Key for Storage Account
Write-Output ""
Write-Output ""
Write-Output "---------------------------- Status ----------------------------"
Write-Output "Getting Storage Account Keys for $StorageAccount ..."
try
{
  $StorageAccountKeys = Get-AzureRmStorageAccountKey -ResourceGroupName $ResourceGroup -AccountName $StorageAccount
  ## Create a Storage Account Context
  ## Try using Key1 then Key2
  try {
    $Context = New-AzureStorageContext -StorageAccountName $StorageAccount -StorageAccountKey $StorageAccountKeys.Value[0]
    Write-Output "Using Storage Account Key 1"
  } catch {
    Write-Output "Failed to create Storage Context with Key 1, trying Key 2"
    try {
      $Context = New-AzureStorageContext -StorageAccountName $StorageAccount -StorageAccountKey $StorageAccountKeys.Value[1]
      Write-Output "Using Storage Account Key 2"
    } catch {
      $Context = $null;
      Write-Output "Failed to create Storage Context with Key 2, exiting"
      Write-Error "Error creating Storage Context using either Account Key"
      throw $_.Exception
      exit
    }
  }
  ## Loop through the list of possible deletes
  $DeleteDate = [DateTime]::Today.AddDays(-$DaysToKeep)
  $PossibleDeletes = 0;
  $Deleted = 0;
  $TotalSize = 0;
  $DeletedSize = 0;
  Write-Output "Searching for actionable Blobs in container"
  $Blobs = Get-AzureStorageBlob -Context $Context -Container $Container $Extension | Where-Object { $_.LastModified -lt $DeleteDate }
  foreach ($Blob in $Blobs) {
    $PossibleDeletes++
    $TotalSize = $TotalSize + $Blob.Length
    Write-Output "Working on " $Blob.Name
    try {
      if (-Not $DryRun) {
        ## This run is for real, do delete
        Remove-AzureStorageBlob -Blob $Blob.Name -Container $Container -Context $Context
      } else {
        ## Dry Run, do not delete, just log
        Write-Output "Dry Run - " $Blob.Name
      }
      $Deleted++
      $DeletedSize = $DeletedSize + $Blob.Length
    } Catch {
      Write-Output "Failed to delete $Blob.Name"                
    }
  }
  $TotalSizeHR = [System.Math]::Round($TotalSize / 1GB, 2)
  $DeletedSizeHR = [System.Math]::Round($DeletedSize / 1GB, 2)
  $FailedToDelete = ($PossibleDeletes - $Deleted)
  Write-Output "Deleted $Deleted of $PossibleDeletes Blobs"
  Write-Output "Cleaned up $DeletedSizeHR GB"
  Write-Output "Failed to delete $FailedToDelete Blobs"
}
catch
{
  Write-Output "Error fetching Storage Account Key"
  Write-Error -Message $_.Exception
  throw $_.Exception    
  exit
}