Open Outlook and go to the folder containing the emails
Select multiple emails by holding Ctrl and clicking each email
Select a range of emails by clicking the first email, then holding Shift and clicking the last email
To select all emails in a folder, press Ctrl + A
Press Delete on your keyboard
Right-click the selected emails and choose Delete
To remove them permanently, empty the Deleted Items folder
On Outlook mobile, tap and hold an email, then tap additional emails to select multiple messages
Tap the Delete icon to remove the selected emails