$path = "C:Userstest"

Get-ChildItem "$path*.*" -include *.data* |
   Sort-Object -Descending -Property LastWriteTime |
      Select-Object -Skip 1 |Remove-Item -Force

Get-ChildItem "$path*.*" -include *.enroll* |
   Sort-Object -Descending -Property LastWriteTime |
       Select-Object -Skip 1 |Remove-Item -Force

Get-ChildItem "$path*.*" -include *.govern* |
   Sort-Object -Descending -Property LastWriteTime |
       Select-Object -Skip 1 |Remove-Item -Force

$sites = @("data","govern","enroll")
$path = "C:Userstest"

for ($i=0; $i -lt $sites.Length; $i++) {
    Get-ChildItem "$path*.*" -include "*.$sites[$i]*" |
        Sort-Object -Descending -Property LastWriteTime |
            Select-Object -Skip 1 |Remove-Item -Force
}