Many users of both Windows 10 & 11 have reported a bothersome pop-up in the notifications area regarding "Windows Backup". This is a light rebranding of OneDrive, essentially trying to get the user to sign in with a Microsoft account & enable the feature. Users are given an option to postpone for a week or 30 days, but after that time the pop-up will reappear. Disabling this notification permanently is quite simple.
STEP 1: Open the Control Panel.
STEP 2A: If Control Panel is viewed by Category, select "System & Security", then pick "Security and Maintenance" from the top of the list.
OR
STEP 2B: If Control Panel is viewed by Icons (large or small), you can directly pick "Security and Maintenance" from that list.
STEP 3: Select "Change Security and Maintenance settings" from the upper left of that window.
STEP 4: You will now be greeted with a menu to "Turn messages on or off". This allows you to toggle several notification options not listed under Settings -> Notifications, but the one we're looking for is to uncheck "Windows Backup" on the bottom half of the screen, under the "Maintenance Messages" screen.
Once that "Windows Backup" setting is unchecked, then the notification should no longer bother the user.