When you set up your email in Mail for Windows 10, a default set of folders is created. You'll see Inbox, Drafts, and Sent at a minimum and may see additional folders such as Archive and or Junk. You can't delete the default folders, but you can add new folders and delete any folders you add.
To create a folder, first choose the email account (if you have more than one account) and then choose More.
Choose the + next to All folders to create a new top-level folder or right-click any existing folder and then choose Create new subfolder.
Give your new folder a name and press the Enter key to save your new folder.
To delete a folder you've created, first choose the email account (if you have more than one account) and then choose More.
Right-click the folder and then choose Delete.
Note: You can't delete any of your default folders. Inbox, Sent, and Drafts are all default folders.
For more information
To learn more about Mail for Windows 10, see Mail and Calendar for Windows 10 FAQ.