Windows 10 has raised several concerns about privacy due to the fact that it has a lot of telemetry and online features. In response to these concerns, Microsoft released a document explaining exactly what data they collect, and now Windows 10 even has a Diagnostic Data Viewer. Most of it seems pretty legit stuff when telemetry is set to basic, but still, if you don't trust them, here's how to prevent Windows 10 from sending your data to Microsoft.

Last update: January 28, 2019

Important: This procedure cannot be reversed without reinstalling Windows. Do not follow this guide if:

• You are not an experienced user
• You need to use a Microsoft Account for any reason (outside of your web browser)
• You need to download anything from the Windows Store (including distros for the Linux subsystem if you want to use it)
• You need to add/remove user accounts to your PC (new accounts will not work properly)

You're doing this at your own risk, I am not responsible for any data loss or damage that may occur.

Let's start.

At the end of the setup process, create a local account, don't use Cortana and turn off everything in the privacy settings.

If you already installed Windows with the default settings, go to Start > Settings > Privacy to turn them off. You should also go to Account and disconnect your Microsoft account because this guide will prevent it from working properly.

Once you get to the desktop, go to Settings > Updates and security, and let it download all the updates. Reboot and repeat until no more updates are available.
This is important because Windows Update may interfere with our activities.

Now open the Store app, and let it download updates too.
Again, this is important because updates would interfere with our activities.
This may take some time.

Now that the system is fully updated, make sure Windows is activated with your license (or KMSPico).

Open the start menu and remove all the applications. Some of them, such as Microsoft Edge, will not have an uninstall option; we'll remove them later.
What's important now is to remove all the OEM software and the shitty games like Candy Crush and Minecraft.

Here's what we need:

• Install_Wim_Tweak: Download this archive, extract it to your Desktop, then move it to C:\Windows\System32. This is a very handy tool that allows us to remove Windows components with a single command. You can delete it from System32 when you're finished with this guide.

We need a command prompt, so click start, type cmd and run it as administrator

We will also need PowerShell, so click start, type PowerShell and run it as administrator

In the command prompt, type:

This will take 1-2 minutes.
Unfortunately, since June 2018, the Windows Security icon in the Start menu can no longer be removed without breaking the system.

If Windows complains about the system being unprotected, right click the notification and hide it.

We will now remove almost all UWP features in Windows. The only UWP app you'll have left will be the settings app.
If you manually install UWP apps later (like cracked UWP games) they may not work properly.

Note: if some of the apps reappear after a few minutes, it's because you didn't wait for the updates to finish. You can simply remove them again using the same commands.

We will use our command prompt and PowerShell to remove everything we can.
The commands in green are for the command prompt; the ones in blue are for PowerShell.

Windows Store

You can ignore any error that pops up.

Music, TV, ...

Alternatives: MPC-HC | VLC | MPV

Xbox and Game DVR

You can ignore any error that pops up

Sticky notes

You can ignore any error that pops up.

Alternatives: Notebot

Maps

Alarms and Clock

You can ignore any error that pops up.

Mail, Calendar, ...

You can ignore any error that pops up.

Alternatives: Thunderbird

OneNote

Photos

Alternatives: JPEGView, or the old Windows Photo Viewer

Camera

Ignore the errors that pop up

Weather, News, ...

Calculator

Alternatives: SpeedCrunch

Sound Recorder

Alternatives: Audacity

Paint 3D and VR features

Reboot (important!) and reopen our command prompt and PowerShell

Microsoft Edge

Right click the Edge icon on your taskbar and unpin it. (Important: don't skip this step, or the icon will be permanently stuck there)

Alternatives: Firefox | Chromium | Iridium Browser | Pale Moon

Contact Support, Get Help

Additionally, Go to Start > Settings > Apps > Manage optional features, and remove Contact Support (if present).

Microsoft Quick Assist

Connect

Your Phone

Snip & Sketch

Hello Face

System Restore

Reboot!

Reboot the system and you're now free of UWP garbage.

With the Anniversary Update, Microsoft hid the option to disable Cortana.
Warning: Do not attempt to remove the Cortana package using install_wim_tweak or the PowerShell, as it will break Windows Search and you will have to reinstall Windows!
Open our command prompt again and use this command:

Reboot again and Cortana is gone. The icon is still there, but it will open the regular search instead.

Note: Windows may say that Indexing is not running, but it will start running again after a few minutes.

Open the command prompt again and get ready to type

Turn off Windows Error Reporting

We will remove the service later, but in case an update reinstalls it, this will at least keep it turned off

No more forced updates

This will notify when updates are available, and you decide when to install them

No license checking

By default, Windows will check your license every time you turn on your PC, this will prevent it

Disable sync

It doesn't really affect you if you're not using a Microsoft Account, but it will at least disable the Sync settings from the Settings app

No Windows Tips

Removing OneDrive

In the command prompt, type the following commands:

Note: since version 1803, the Task View feature depends on CDPUserSvc and its other services. They can no longer be removed without breaking this feature.

Press Win+R, type regedit, press enter, and navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

Here we need to locate the follwing keys:

• DPS
• WdiServiceHost
• WdiSystemHost

Right click the key and select Permissions, then click Advanced, change the Owner to your username, check "Replace owner on subcontainers and objects" and "Replace all child object permission entries with inheritable permission entries from this object", if inheritance is enabled, disable it and convert to explicit permissions, apply, remove all the permission entries and add one for your username with Full control, confirm everything and delete the key.
Repeat for the 3 keys and you're done.

Windows 10 has a huge amount of scheduled tasks that may report some data. Type these commands in the command prompt to remove them:

Some of these may not exist, it's fine.

We must disable Windows Spotlight, and other "Suggestions".
Go to Start > Settings > Personalization:

• Under Lock screen and set the background to Picture
• Under Start set Show suggestions occasionally in Start to off (They're literally ads)

• Set Get tips, tricks, and suggestions as you use Windows to off
• Set Show me the Windows welcome... to off

• Set Show suggestions occasionally in your timeline to off

• Under General, turn off everything
• Under Activity history, turn off everything
• Under Speech, turn off everything
• Under Inking, turn off everything
• Under App diagnostics, set Let apps access diagnostic information to off

• Under Permissions & History, turn off everything

• Right click the people icon and uncheck "Show People button"

Later on, you might get a "Suggestions" notification. Right click it and turn it off.

For some applications (such as the settings app), the only way to prevent them from reporting data is to block them with a firewall. This is why you should use a firewall to block all traffic except what you explicitly allow.
Personally, I allow Windows Update, Network discovery and sharing, DHCP, DNS, my web browser and nothing more. This will limit the traffic of undesired applications to DNS queries, they won't be able to send or receive anything.

Option 1: TinyWall

TinyWall is my favorite, but the installer no longer works on Windows 10 1803 because of an issue with digital signatures. I'm sure the author will fix this soon, but in the meanwhile, I made a modified installer without the problematic signature.
Setting up the firewall may take some time, but you'll be as safe as you could possibly be when using Windows. Tinywall's autolearn feature is very useful when you install a new application: it will learn its patterns and allow them through the firewall.
A big limitation of Tinywall, if you decide to use it, is that you cannot allow/block individual UWP apps (for instance, allow Facebook but not Candy Crush). Blocking C:\Windows\System32\WWAHost.exe (recommended) will block all of them, while allowing it will allow all of them to go through.
Microsoft Edge is the only exception and has its own exe files. The same thing happens if you use the UNIX subsystem, there is no way to block specific applications.

Option 2: SimpleWall

SimpleWall works pretty much in the same way that TinyWall does but the UI is a bit more basic, it doesn't have the autolearn feature of TinyWall, and exe files must be added one by one for apps like Steam or git that have many executables.
Unlike TinyWall however, this firewall can block individual UWP apps, which is a nice feature.

Things will change in the future, and I'll do what I can to keep this guide updated.
As of September 2018, this guide works on Windows 10 Pro.

When a major update is installed, almost all changes will be reverted and you'll have to repeat this procedure. Major updates come out about twice a year.