I don't need as far as I know “Microsoft AU Daemon” so how can it be disabled? this message is annoying - can I disable it or remove the application as I only use Word, Excel and Powerpoint. Just to be clear this is on a mac with Sierra 10.12.5 and Excel 15.32 Cheers.

Note, I have asked this on Superuser as well.
"Microsoft AU Daemon" stands for "Microsoft Auto Update Deamon". I recommend checking for Updates regularly, since MS is updating their products quite frequently.

You cannot really 'turn off' the update-check, but you can set it to check for updates manually. In order to do that you should look at the Office Support Pages found here.

In short: Start Word f.e., in the Menu-Bar click on "Help", then click on "Check for updates". The MS Autoupdate starts and in that window you can select "Manually Check" and close the Window. After that the "Microsoft AU Daemon" should not start again unless you manually check for update.