Q: iCloud sync crashes Safari 10

I installed Safari 10 and it crashes, both in El Capitan and Sierra.  I narrowed down the crash to iCloud Safari data, by doing a clean install of Sierra, and after logging into iCloud with my AppleID, enabling the information stored in the iCloud one by one.  Safari worked fine  until I enabled Safari in the iCloud settings.  Now it crashes every time it is started.  I unchecked Safari in the iCloud settings, and it still crashes!

I have turned off Safari in iCloud on all of my devices, but there is evidently still Safari data in my iCloud, which Safari 10 does not like.  Syncing Safari on any other device does not cause a problem.

So, how can I clear my Safari data from iCloud?