1. Press WIN+R keys together to launch RUN dialog box. Now type gpedit.msc and press Enter. It'll open Group Policy Editor.
2. Now go to:
Computer Configuration -> Administrative Templates -> Windows Components -> Windows Update -> Windows Update for Business
3. In right-side pane, look for following option:
Select the target Feature Update version
4. Double-click on the option and select Enabled option.
Now type the desired Windows 10 version which you want to lock in your device in the given text box.
For example, if you are using Windows 10 version 1909 in your device and want to stay on the same version, type 1909 in the text box.
PS: You can check installed Windows 10 version using winver command in RUN dialog box or Start search box as mentioned here. The installed Windows 10 version is shown in the 2nd line.
Click on Apply and OK buttons.
That's it. Now Windows 10 will stay on the selected version in your device.
PS: In future, if you decide to upgrade to new Windows 10 version, Set the above mentioned option to Not Configured in Group Policy Editor and check for new updates in Windows Update.
METHOD 2: Using Registry Editor
If you are using Home edition of Windows, you'll not be able to run gpedit.msc command because this edition doesn't come with Group Policy Editor.
If you can't use or don't want to use Group Policy Editor, you can take help of Registry Editor for the same task. Just follow these simple steps:
1. Press WIN+R keys together to launch RUN dialog box. Now type regedit and press Enter. It'll open Registry Editor.
2. Now go to following key:
3. In right-side pane, right-click on empty area and select New -> DWORD (32-bit) Value option. Set the new DWORD name as TargetReleaseVersion and set its value to 1
Again right-click on empty area and select New -> String Value option. Set the new String name as TargetReleaseVersionInfo and set its value to desired Windows 10 version such as 1909
4. Close Registry Editor and restart your computer to take effects.
Now Windows 10 should keep using your desired version in your computer system.
PS: In future, if you decide to upgrade to new Windows 10 version, delete the DWORD and String values created in above mentioned steps from Registry Editor. Restart your computer and check for new updates in Windows Update.