How to disable Ctrl+Shift keyboard layout switch (for the same input language) in Windows 10?

The new path to this configuration :

• Open PC Settings
• Go to Time & language
• Click Region & Language
• Click Advanced keyboard settings
• Click Language bar options
• Go to the Advanced Key Settings tab
• Click Change key sequence...
• Set one or two of the "Not assigned" options
• Click OK

More recent versions of Windows 10 no longer have the Regional & Language Settings dialog, and the Language Bar Options have been moved to the Advanced Keyboard Settings page.

Now just search for "Language bar" from the Windows search tool and you'll get to an "Advanced keyboard settings" page, then click on "Language bar options" and there you are.

On Windows 10 1809 (August 2019):

Full route:

1. Settings App (start menu -> cog icon)
2. Time and language
3. Language (sidebar)
4. Spelling typing and keyboard settings (Under Related Settings, Blue text)
5. Advanced keyboard settings
6. Language bar options
7. Advanced key settings (tab)
8. Select, in the Hotkeys for input languages group box, in the list view, the row Between input languages
9. Click Change Key Sequence button
10. Set both radio buttons to Not Assigned

Alternative:

1. Search for Typing settings on the start menu
2. Go to step 5

The path to access these settings is likely to change on future releases.

Windows 10:

1. Press Windows+R (run)
2. "C:\Windows\system32\rundll32.exe" Shell32.dll,Control_RunDLL input.dll,,{C07337D3-DB2C-4D0B-9A93-B722A6C106E2}
3. Go to the Advanced Key Settings tab
4. Click Change Key Sequence button
5. Set both radio buttons to Not Assigned