Windows 10 - Disable Logon Screen Background
How to disable the Lock Screen image background in Windows 10?
Is there a way by using a registry key (Windows Registry)?
In Windows 10 is possible to disable the Lock Screen/Logon screen background image by using the Windows Registry in the following way:
Open Registry Editor by typing regedit in the Search field, or by pressing Windows key + R and typing regedit.
Use the folder tree on the left to navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System
On the right side of the Registry Editor, click the right mouse button, select New, then 32-bit DWORD value and set its name to DisableLogonBackgroundImage. Double click it, and set its value to 00000001 or simply 1.
Now close the Registry Editor and restart your computer and you should have solid color instead of background image while logging in.
If for some reason you want to revert these changes, you just need to find DisableLogonBackgroundImage located in HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System and set its value to 00000000 or just delete it.