I have the Lumia Cyan update for my ATT 1520 and re-enrolled in the preview for developer's program. But I'm no longer interested in it, and I'm tired with all the notifications about downloading updates and the like. How can I make that stuff go away?
did you reinstall the app? if yes, just tick the box to re-enroll.
then exit to your home screen, go back to the app, UN-tick the box
and tap done. after that, UN-install the app.