Remove Outlook 365 Filter

Hi all

I have updated from Office 2016 ProPlus to Office 365 ProPlus today but have a bit of a bugbear I cant get rid of.

In the top bar of Outlook there now appears to be a filter drop down that causes the bar to be quite large (and a bit annoying). 

I can't for the life of me find out how to remove this (or even if it can be removed).

Any help would be much appreciated!