Outlook 2016 - Cannot delete reminders
How to clear Outlook 2016 reminders that just won't die.
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I've been running into an issue recently where my Outlook 2016 for Mac would constantly bring up reminders that I had already dismissed. I noticed it seemed to be related to using Outlook on another Mac for the same Exchange account - I.e. As soon as I did it on another Mac, then boom all the reminders were back on *all* machines.
It's irritating, but not catastrophically so I guess.
Anyway, after doing some research there's a fix that seems to sort it. Firstly, shut down the Outlook 2016 for Mac client on all of your Macs.
Go to the user's library folder - you can do this by selecting the 'Go' menu in Finder, selecting 'Go to Folder' and entering '~/Library':

Under the home user's library, navigate to:
/~Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile/Data/Events
…then just delete all the folders/contents of that directory. Do that on all of your Macs.
Once done, fire up Outlook and they should stop popping up in such an annoying fashion.