Deleting Specific Files in VB.NET - vb.net

Question

I am trying to figure out the code on Visual Basic after I have already extracted all files from a folder that was in a flash drive and put them in a folder on the computer. How could I have this program delete all the files that have not been modified from a previous date in the folder on the computer?
This is what I have so far:
Imports System.IO
Public Class frmExtractionator
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
Dim sourceDirectory As String = "E:\CopierFolderforTestDriveCapstone"
Dim archiveDirectory As String = "E:\FilesExtracted"
Try
Dim txtFiles = Directory.EnumerateFiles(sourceDirectory)
If(Not System.IO.Directory.Exists(archiveDirectory )) Then
System.IO.Directory.CreateDirectory(archiveDirectory)
End If
For Each currentFile As String In txtFiles
Dim fileName = currentFile.Substring(sourceDirectory.Length + 1)
File.Move(currentFile, Path.Combine(archiveDirectory, fileName))
Next
Catch eT As Exception
Console.WriteLine(eT.Message)
End Try
End Sub
End Class

Answer 1

Something like this will delete files that have not been modified since the given date.
Private Sub DeleteUnmodifiedFiles(directoryName As String, modificationThreshold As Date)
Dim folder As New DirectoryInfo(directoryName)
Dim wasModifiedSinceThreshold As Boolean
For Each file As FileInfo In folder.GetFiles
wasModifiedSinceThreshold = (file.LastWriteTime > modificationThreshold)
If (Not wasModifiedSinceThreshold) Then file.Delete()
Next
End Sub
To delete based on a number of days...
Private Sub DeleteUnmodifiedFiles(directoryName As String, modificationThresholdDays As Integer)
Dim folder As New DirectoryInfo(directoryName)
Dim thresholdDate As Date
Dim wasModifiedSinceThreshold As Boolean
For Each file As FileInfo In folder.GetFiles
thresholdDate = DateTime.Now().AddDays(-1 * modificationThresholdDays)
wasModifiedSinceThreshold = (file.LastWriteTime > thresholdDate)
If (Not wasModifiedSinceThreshold) Then file.Delete()
Next
End Sub