How to permanently turn off upper left slide out notifications about iCloud not syncing

To permanently stop iCloud sync notifications on macOS Sonoma 14.6.1 when you do not use iCloud, you need to sign out of your Apple Account/Apple ID within System Settings. 

Sign Out of Apple Account

1. Click the Apple menu () in the upper-left corner of your screen.
2. Select System Settings.
3. Click your name (Apple Account / Apple ID) at the top of the sidebar.
4. Scroll down to the bottom of the right panel and click Sign Out
5. Choose whether to keep a local copy of any data on your Mac when prompted, then confirm.