I was surprised that there is no easy way to remove bookmarks from PDF.
pdftk can't do it, ghostscript same AFAIK, qpdf... and there are no other significant tools that I'm aware of
Easiest for me right now is PDF Mod GUI, which removes bookmarks one by one - user has to click on parent bookmark and press remove, so on for all top level nodes which is silly
Also I know there are probably some Java GUIs that can do it, but I don't want to load java just to remove bookmarks when I need to
I could also accept some programmatic solution, python, perl ...