Log in to Outlook from your desktop computer. Select the emails you would like to archive. If required, use the search box that appears on the screen’s far left side. If you want to select all emails, press Ctrl+A. When you’re done selecting, click the archive button from the top of the Outlook page.
If you would like to create a separate folder for the emails being archived, you might want to click on the “Create Archive Folder” first and then archive your emails to that folder.