A Microsoft file hosting and synchronization service.
If I get it right, it should still work on Mojave. Maybe try to completely uninstall it. Uninstall it via Programs and remove all folders which are left.
These are the paths in which data could be left:
- ~/Library/Application Support/
- ~/Library/Containers/
- ~/Library/Caches/
- ~/Library/Preferences/
- ~/Library/Cookies/
- ~/Library/Logs/
- ~/Library/LaunchAgents/