If you are fed up with your daily advertising banner in the desktop version of outlook pushing you to the mobile app version, here is the page detailing how to remove it. How to remove the Get and set up Outlook Mobile app on my phone option from Outlook
OF COURSE you should not have to opt out of these kind of ads in your paid version, and OF COURSE it should be simple and not some vague and for many people scary registry hack, but hey, that seems to be the world we live in these days…
This kind of nonsense is a good reason to revert back from the changing-under-your-hands cloud versions and back to solid versions that give you the same experience for the entire duration of it’s use.