Microsoft's voice-controlled AI assistant on Windows 10 is actually pretty good, certainly better than some rival setups such as Samsung's Bixby. However, as with many such assistants, while they can be a boon, they're not to everyone's tastes and if you don't want their help they can be a royal pain in the ass.

Microsoft has further integrated Cortana over time, and it's now not as easy to disable the feature as it once was, where you simply toggled it on or off via straightforward menu system.  Now the process is much more involved, and in its current form, if you disable it fully, it will impact the search function - it can even according to some reports break search completely, requiring a full re-install of Windows 10 to fix it. Needless to say, you proceed at your own risk.

It's not hard to imagine that in future updates Microsoft could completely prevent users from disabling Cortana, however.

The most basic level of switching Cortana off doesn't involve disabling it completely, but instead prevents the assistant from learning about you, your habits, and your data. Other methods involve disabling speech and typing data gathering, turning off Cortana fully, and the specifics of disabling Cortana on Windows 10 Pro, which is a little different from Windows 10 Home.

Turning Off Cortana's User Analytics

1. Click either the "Search" box or Cortana's icon near the Start menu.
2. Click the gear icon to open Cortana's "Settings" menu. 
3. Turn every toggle to the "Off" setting.
4. A the top of the Settings menu click on "Change What Cortana Knows About Me".
5. This will bring up a page called "Personal Information". At the bottom click "Clear".

Turning Off Cortana's Typing & Voice Data

1. Open the Start menu.
2. Click the Settings gear icon.
3. Select Privacy.
4. On the left side look for a section called "Speech, Inking & Typing".
5. Click the option for "Stop Getting To Know Me".

How To Fully Disable Cortana On Windows 10 Pro

The steps outline above will stop Cortana from analysing you and your computer use, and it will no longer respond to voice commands. However, it is still active in the background. To fully disable it on Windows 10 Pro, follow these steps:

1. Open the Start menu.
2. Search for "Edit Group Policy", then open it.
3. Go to Computer Configuration > Administrative Templates > Windows Components > Search.
4. Find "Allow Cortana" and double-click to open it.
5. Click "Disabled" then click OK.

How To Fully Disable Cortana On Windows 10 Home

This is quite complicated and involves editing Windows Registry - if you're not familiar or comfortable with this process you can either make a backup and restore point before attempting it, or get someone else to do it for you.

1. Open the Start menu.
2. Search for "regedit", then open it.
3. Navigate to HKEY_LOCAL_MACHINE > SOFTWARE > Policies > Microsoft > Windows.
4. Right-click the Windows directory.
5. Choose New > Key.
6. Type in "Windows Search" (no quotations), and hit enter.
7. Select Windows Search.
8. On the right, right-click in the empty area and choose New > DWORD (32-bit) Value.
9. Type in "AllowCortana" (no quotations), and hit enter.
10. Double-click "AllowCortana", and type in 0 under Value Data.
11. Restart your computer. Cortana should now be fully removed - if you want it back you'll need to do a full re-install of Windows 10.
12. You can confirm if Cortana is gone as instead of “Ask Me Anything”, the new search box should instead simply say “Search Windows”.