There are a couple of things to do as there are two syncing methods:
The 1st method is the account itself via windows -
whereas previously advised by others on here, go to account , privacy etc and slide all the sliders to the left.
2nd. If you STILL have the GREEN SYNC icon under the account/profile name then it is likely the CLOUD/ONE DRIVE that is causing this -(even if you are not logged in/using One drive)
The super simple method is to go to the Application Tray in the Lower right part of your taskbar and then RIGHT CLICK the ONE DRIVE icon - Click on the settings wheel and then select UNLINK THIS DEVICE -
- Open the system tray icon. Open/Right click "ONE DRIVE" icon, Click on the gear icon then choose "Settings" option.
- Then under the Accounts tab select the "Unlink this PC" option.
- Follow the on-screen prompts to unlink your account and close the Window.
Boom! you will now be fully unsynced and the GREEN "syncing" icon will have disappeared.
Hope this helps as it worked fully for me on WIN 11
if it works for you then please give a helpful thumbs up