Windows 10 disable automatic defragmentation

How to disable automatic defragmentation in Windows 10? It is scanning my 2 TB HDD for 2 hours already and lags too much.

In addition to the method geotavros described, another method for turning off automatic defrag/optimization can be accomplished by doing the following....

1. Click on the Start Menu
2. Start typing Defrag and you'll see an option come up called Defragment and Optimize Drives. Select that.
3. Make sure the drive you want to turn off defrag/optimize is highlighted and then click on Change Settings.
4. Uncheck the box that says Run on a schedule
5. Click on OK and you're done.

Alternative process with Command Prompt::

• Run Command Prompt as administrator and run the command schtasks /Delete /TN "\Microsoft\Windows\Defrag\ScheduledDefrag" /F

• /TN option specifies the path\name of the task to delete.

• /F option forcefully deletes the task and suppresses warnings if the specified task is currently running.

Open an administrative cmd prompt (or Powershell, up to you) and execute:

schtasks /Change /DISABLE /TN "\Microsoft\Windows\Defrag\ScheduledDefrag"

This command disables the task, just as the original question asks and is a faster, cmd line-based solution that functions identically to the top GUI answer from n8te.

This doesn't delete the task, which means that if you decide you need it enabled again at a later date, simply change DISABLE to ENABLE and run again in an elevated admin prompt:

schtasks /Change /ENABLE /TN "\Microsoft\Windows\Defrag\ScheduledDefrag"

You can disable it via the Task Scheduler > Task Scheduler Library > Microsoft > Windows > Defrag > then disable the "ScheduledDefrag".