Disable "automatic maintenance" in Windows 8

You can do it by task scheduler. For this open the task scheduler by typing task on the Modern UI under the Apps and you will find the Task Scheduler at the left side click it and open. Now go to following path

Task Scheduler > Microsoft > Windows > Task Scheduler

Here you have to right click on the Idle Maintenance & Regular Maintenance and select the option disable, that's it!

If you want to enable it again then just do the reverse.

Automatic maintenance does too many functions, like the updating of Windows software etc. so that turning it totally off is not advisable (or possible).

To complete the answer by nhinkle, one could at least disable it from waking your PC.

This is done in Action Center / Maintenance section / Change maintenance settings, uncheck "Allow scheduled maintenance to wake up my computer".

Together with setting the scheduled time to late at night or a time that it won't be a bother (3 AM is the default), is about the maximum possible solution.

The Automatic Maintenance task is a built-in scheduled task, but if you think you can just open task scheduler as an administrator and disable it you’re wrong. It will just re-enable itself on Servre 2012 as @abstrask pointed out. You'll need to use the psexec utility (Sysinternals) together with schtasks.exe, and you need to run the command as SYSTEM. Use the following command:

psexec \\SERVERNAME -s schtasks /change /tn "\Microsoft\Windows\TaskScheduler\Maintenance Configurator" /DISABLE

In my scenario, I was testing this on my Hyper-V host, so I simply skipped the \SERVERNAME switch.

psexec -s schtasks /change /tn "\Microsoft\Windows\TaskScheduler\Maintenance Configurator" /DISABLE

Command to run

After you run the command, you can verify the task is now disabled in the Task Scheduler