param( 
    [string]$url
)

function Remove-Custom-Action($site, $actionUrl)
{
    Write-Host "Remove custom action $actionUrl from" $site.Url -foregroundcolor green
    $actions = $site.UserCustomActions
    $contains = $false
    foreach ($a in $actions)
    {
        #Write-Host "    " $a.ScriptSrc
        if ($a.ScriptSrc.ToLower().Contains($actionUrl.ToLower()))
        {
            $contains = $true
            $a.Delete()
            Write-Host "    Custom action is removed" -foregroundcolor yellow
            return
        }
    }
    
    if (!$contains)
    {
        Write-Host "    Custom action is not found" -foregroundcolor yellow
        return
    }
}

if (-not $url)
{
    Write-Host "Specify site url in url parameter" -foregroundcolor red
    return
}

$webApp = Get-SPWebApplication $url
$webApp.Sites | ForEach-Object { Remove-Custom-Action $_ "CustomAction.js" }