cd C:\Temp\!

function Get-LogSize($p) {
    return (Get-ChildItem $p | Measure-Object -property length -sum).Sum;
}

Get-ChildItem |
    Sort-Object -Property CreationTime |
    Select-Object Name,@{Name="Size";Expression={Get-LogSize($_)}} |
    ##Group-Object Size > ..\after.txt
    Group-Object Size |
    ForEach-Object { $_.Group | Select-Object -Skip 1 | ForEach-Object { Remove-Item $_.Name -Force -Recurse } }