What is Clutter/Focused Inbox anyway?
Clutter analyzes how you process your emails and determines what is unimportant to you. It then moves unimportant emails automatically from your Inbox folder and places them into the Clutter folder. In theory, this should leave you with an emptier and distraction-free Inbox folder.
Basically, the Clutter or "Focused Inbox" folder is your “second-tier” Inbox folder containing emails that you usually ignore.
However, if you don't want Outlook to automatically separate your email into Clutter, you can turn it off.
How to Turn Off Clutter/Focused Inbox
Open email in a web browser.
Once logged in, you should automatically be routed to your main inbox. At the top of the Inbox, above the emails, there should be two options labeled "Focused" and "Other". There should also be a "Filter" option to the right of these tabs.
Click on the "Filter" option, and a drop down menu should appear. Click on the "Show Focused Inbox" option so that it is unchecked as in the picture below.
The Clutter/Focused Inbox function is now disabled.