How do I delete iCloud synched Safari bookmarks on MacOS X so that they don't return?

First, I turn off bookmark sync on all of my devices (MacPro, MacBook Pro, 2 iPads and an iPod touch). The iOS devices ask if I want to delete bookmarks and I say "tes."

Second, I start deleting all of the many, many dupes and unwanted bookmarks. After great effort, I am satisfied with the result.

Third, I turn bookmark syncing back on for my MacPro. That's when the deleted bookmarks start returning. It's veritable whac-a-mole game but it isn't much fun at all.

I need to clean up my act but iCloud won't let me do it.