How do I log out of iCloud

How do you log out on a MacBook Pro 13 inch 2015

Sign out on your Mac

1. Choose Apple menu  > System Preferences.
2. Click Apple ID, then click Overview. If you use macOS High Sierra or earlier, click iCloud.
3. Click Sign Out.
4. If you want to a keep a copy of your iCloud data on your Mac before you sign out, make sure that you select the appropriate checkboxes. Then click Keep a Copy.
5. If you want to keep a copy of your Safari passwords on your Mac, click Keep on This Mac.

*Graphic is the example from the linked Apple support document.

On what device?

Look at this document.

How do you log out on a MacBook Pro 13 inch 2015