While you can disable the "Idle Maintenance" and "Maintenance Configurator" tasks, under \Microsoft\Windows\TaskScheduler, they will get re-enabled by the "Maintenance Configurator" task, which by default runs at 01:00 every day. In addition, it has two custom triggers, which cannot be viewed or edited using the Task Scheduler console.
Even as an admin, you don't have permission to disable the "Maintenance Configurator" task, though I haven't tried any "tricks" to do so - If Microsoft has gone through these lengths to prevent you from disabling it, it's probably a bad idea to do.
The relatively "clean" way I found to disable Idle and Regular Maintenance, that seems to still work after the "Maintenance Configurator" task has run, is to disable the triggers of the "Idle Maintenance" and "Maintenance Configurator" tasks.
The task will remain enabled, but with triggers disabled, it won't actually start.
(My answer is based on Windows Server 2012, which also has this "feature". I'm assuming it's setup the same way. Correct if I'm wrong)