I know this is not a new issue and I have read multiple cases where it seems that there are no real solutions yet but I thought I would ask just to make sure.
Despite multiple attempts to remove bookmarked sites, they will repopulate in a few minutes. Even when removed and then imported from a saved file.
Expect that bookmark changes are applied to synced browsers. I have broswers on multiple macs running 10.12 - 10.14, multiple windows 10 pcs, and a few linux boxes (Ubuntu 18).
Version 0.68.132 Chromium: 76.0.3809.132 (Official Build) (64-bit)