Hello Jim
Thank you for participating in the Microsoft Community, My name is Miguel T. I'm an independent Advisor
Login to https://portal.office.com - Top right click your icon and select "My Account". In here in the top right again click the cog, then down at the bottom under "Your app settings" select "Mail".
Now, you will see the previous Owa Version where you can use the cleanup option.
As workaround you can use this link also:
https://outlook.office365.com/owa/?path=/option...
I hope this information has been useful, please let me know if you still need assistance.