Deleting unwanted emails using the select all features

I am currently using New Outlook email system. When ever I open my in box, there are two categories. Focused, and other. Let's assume I choose, Other. Let's assume there are say 15 emails. I look down that list and I have determined that I really would not open any of them, so I choose to just delete them all. I have always able to check the "select" box that would provide another box that automatically selects all the email, then simply click the trash can icon. However, I can no longer check the 'select' box. Why?