Open Outlook and go to the folder you want to clean
Click the first email
Hold Shift and click the last email to select a range
Press Delete
To select all emails in a folder, press Ctrl+A
Press Delete
To permanently remove selected emails, press Shift+Delete
To delete emails by sender, use the search box to find the sender
Press Ctrl+A to select the search results
Press Delete
To delete emails by date, search using date filters
Press Ctrl+A to select the filtered emails
Press Delete
To delete emails in bulk from multiple folders, repeat the process in each folder
To empty the Deleted Items folder, right-click it and choose Empty Folder
To remove all mail from an account, use File, then Account Settings, then remove the account if needed