This method will introduce a VBA to delete all subfolder of a certain folder in bulk in Outlook. Please do as follows:

1. In the mail view, select the specified folder whose all subfolders you will remove.

2. Press Alt + F11 keys together to open the Microsoft Visual Basic for Applications window.

3. Click Insert > Module, and then paste below VBA code into the new module window.

Sub Delete_All_SubFolders()
Dim oCurrFolder As Folder
Dim oSubFolders As Folders
Dim i As Long

On Error Resume Next

Set oCurrFolder = Outlook.Application.ActiveExplorer.CurrentFolder
Set oSubFolders = oCurrFolder.Folders

For i = oSubFolders.Count To 1 Step -1
oSubFolders.item(i).Delete
Next
End Sub

4. Press F5 key to run this VBA. And now you will see all subfolders under the selected folder are remove in bulk as soon as possible. See screenshot:

Quickly search and delete duplicate emails in Outlook

With Kutools for Outlook’s Duplicate Emails feature, you can quickly find and delete them from multiple mail folders, or find and delete all duplicates from the selected ones with two clicks in Outlook.

Please follow below steps to delete multiple folders in bulk from Microsoft Outlook.

1. Right click the email account whose folders you will delete in bulk, select New Folder from the context menu, and then name the new folder as Temp. See screenshot below:

2. Now drag one of the folders you will delete to the new Temp folder, drop it until the new Temp folder is highlighted. See screenshot:

3. Now a Microsoft Outlook dialog box will pop out and ask for your confirmation about moving the selected folder. Please click the Yes button. See screenshot above.

4. Repeat above Step 2-3 until all folders you will delete are moved to the new Temp folder.

5. Right click the new Temp folder, and select Delete Folder from the context menu. See screenshot below:

6. In the warning Microsoft Outlook dialog box, please click the Yes button. See screenshot above.

So far all folders you need to delete have been removed in bulk.

Copy automatic/conditional formatting to other folder in Outlook

Count the total number of items (emails) in all folders in Outlook