On your old device, the exact opposite will happen if you upgrade. If you don't need any of the new iOS 7/8/9 features then leave it on iOS 6.It still does everything we need it to do on IOS6. Will leave it until it needs a newer iPad . Just thought IOS9 might be more efficient and faster.
There is no option to disable iOS update notifications. It sounds like in your case the update has downloaded already in which case you should be able to go to manage your storage in settings and delete it from there so that it doesn't prompt you anymore, but that option only exists as of iOS 7.1, so might not be helpful in your situation.Also running io6 on ipad2, my 4s still running as new on ios6 and great as a work phone. My iphone 6 won't be seeing ios 10,
Updates are disabled in settings, but i still get ios9.2.1 notifications, each time i need to carefully click 'remind me later'.
WHERE is my cancel or disable option???
iOS7.1.2 ran fine on the iPad2, but iOS9.2.1 is a mess. Extremely slow, and apps crash constantly. Do NOT upgrade.
There is no option to disable iOS update notifications. It sounds like in your case the update has downloaded already in which case you should be able to go to manage your storage in settings and delete it from there so that it doesn't prompt you anymore, but that option only exists as of iOS 7.1, so might not be helpful in your situation.