public bool DeleteFolder(
	string folderName
)

Public Function DeleteFolder ( 
	folderName As String
) As Boolean

// To use the code below, import MailBee namespaces at the top of your code
using MailBee;
using MailBee.ImapMail;

// The actual code (put it into a method of your class)
Imap imp = new Imap();

// Connect to the server and log in the account.
imp.Connect("imap4.company.com");
imp.Login("jdoe@company.com", "secret");

FolderCollection folders = null;

// We may need to iterate through folders collection multiple
// times. For instance, if certain folder to be deleted contains
// subfolders, we should delete this subfolders first and then
// try again. However, using folders.Reverse() optimization
// reduces the number of iterations. Without Reverse, subfolders
// usually appear in the end of the list (thus, all parent folders
// which are in the beginning of the list could not be deleted during
// the first iteration). With Reverse, subfolders will come before
// their parent folders in the list. Thus, if we use Reverse and
// the mail server always returns parent folders before their
// subfolders, we'll delete all the folders in a single pass.
for (;;)
{
    bool deletedAnything = false;
    int processedCount = 0;

    // Get the list of folders in descending order (so that
    // subfolders come first). Alternatively, we could use
    // 'for' loop (instead of 'foreach') with descending
    // counter variable (i.e. i-- instead of i++).
    folders = imp.DownloadFolders();
    folders.Reverse();

    foreach (Folder imapFolder in folders)
    {
        if (!imapFolder.IsValid)
        {
            Console.WriteLine("IMAP4 folder list is corrupted");
            break;
        }
        else
        {
            string folderName = imapFolder.Name.ToLower();

            // Check folder names in case-insensitive manner...
            if (folderName == "inbox" ||
                folderName == "sent" ||
                folderName == "drafts")
            {
                processedCount++;
            }
            else
            {
                try
                {
                    // ...but pass original name when deleting.
                    imp.DeleteFolder(imapFolder.Name);

                    // Remember this deletion attempt succeeded.
                    processedCount++;
                    deletedAnything = true;
                }
                catch (MailBeeImapNegativeResponseException e)
                {
                    // If the server responded with "NO" response,
                    // it usually means the folder contains,
                    // sub-folders so we need to delete them first
                    // (i.e. that's normal situation). If, however,
                    // the response is BAD, this is the real problem,
                    // and we'll re-throw the exception in this case.
                    if (e.CompletionResult != "NO")
                    {
                        throw;
                    }
                }
            }
        }
    }

    if (processedCount == folders.Count || !deletedAnything)
    {
        // If we successfully processed all the folders or
        // no folders have been deleted during the last iteration,
        // it means we deleted everything we should or could.
        break;
    }
}

// Display the list of folders remained after performing clean-up.
folders = imp.DownloadFolders();
foreach (Folder imapFolder in folders)
{
    Console.WriteLine(imapFolder.Name);
}

imp.Disconnect();

' To use the code below, import MailBee namespaces at the top of your code
Imports MailBee
Imports MailBee.ImapMail

' The actual code (put it into a method of your class)
Dim imp As New Imap

' Connect to the server and log in the account.
imp.Connect("imap4.company.com")
imp.Login("jdoe@company.com", "secret")

Dim folders As FolderCollection = Nothing

' We may need to iterate through folders collection multiple
' times. For instance, if certain folder to be deleted contains
' subfolders, we should delete this subfolders first and then
' try again. However, using folders.Reverse() optimization
' reduces the number of iterations. Without Reverse, subfolders
' usually appear in the end of the list (thus, all parent folders
' which are in the beginning of the list could not be deleted during
' the first iteration). With Reverse, subfolders will come before
' their parent folders in the list. Thus, if we use Reverse and
' the mail server always returns parent folders before their
' subfolders, we'll delete all the folders in a single pass.

Do
    Dim deletedAnything As Boolean = False
    Dim processedCount As Integer = 0

    ' Get the list of folders in descending order (so that
    ' subfolders come first). Alternatively, we could use
    ' 'For' loop (instead of 'For Each') with descending
    ' counter variable (i.e. 'i -= 1' instead of 'i += 1').
    folders = imp.DownloadFolders()
    folders.Reverse()

    For Each imapFolder As Folder In folders
        If Not imapFolder.IsValid Then
            Console.WriteLine("IMAP4 folder list is corrupted")
            Exit Do
        Else
            Dim folderName As String = imapFolder.Name.ToLower()

            ' Check folder names in case-insensitive manner...
            If folderName = "inbox" OrElse folderName = "sent" OrElse _
                folderName = "drafts" Then

                processedCount += 1
            Else
                Try
                    ' ...but pass original name when deleting.
                    imp.DeleteFolder(imapFolder.Name)

                    ' Remember this deletion attempt succeeded.
                    processedCount += 1
                    deletedAnything = True

                Catch e As MailBeeImapNegativeResponseException
                    ' If the server responded with "NO" response,
                    ' it usually means the folder contains,
                    ' sub-folders so we need to delete them first
                    ' (i.e. that's normal situation). If, however,
                    ' the response is BAD, this is the real problem,
                    ' and we'll re-throw the exception in this case.
                    If e.CompletionResult <> "NO" Then
                        Throw
                    End If
                End Try
            End If
        End If
    Next

    If processedCount = folders.Count OrElse Not deletedAnything Then
        ' If we successfully processed all the folders or
        ' no folders have been deleted during the last iteration,
        ' it means we deleted everything we should or could.
        Exit Do
    End If
Loop While True

' Display the list of folders remained after performing clean-up.
folders = imp.DownloadFolders()
For Each imapFolder As Folder In folders
    Console.WriteLine(imapFolder.Name)
Next

imp.Disconnect()