PurgeOldPerfmons.ps1. Attach this to a scheduled task that runs the perfmon. An alternative to fighting with Data Manager settings.

PurgeOldPerfmons.ps1

$perfLogsFolder = "C:\Perflogs"
$numberOfDirectoriesToKeep = 3

# Check to see if we need to clean up old nmcap files
$directories = new-object 'System.Collections.Generic.List[string]'
$directories.AddRange([System.IO.Directory]::GetDirectories($perfLogsFolder))
while ($directories.Count -gt $numberOfDirectoriesToKeep)
{
    $oldestFileTime = [DateTime]::MaxValue
    $oldestFileName = ""
    foreach ($directory in $directories)
    {
        $fileTime = [System.IO.Directory]::GetCreationTime($directory)
        if ($fileTime -lt $oldestFileTime)
        {
            $oldestFileTime = $fileTime
            $oldestDirectoryName = $directory
        }
    }
    
    [System.IO.Directory]::Delete($oldestDirectoryName, $true)
    $directories.Remove($oldestDirectoryName)
}