I think suggesting using the rails console at this stage is a little overkill. It’s only really an option for a sysadmin, and even then I’d say ‘advise with caution’.
If bookmarks are causing some kind of issue with the site and can’t be deleted through the UI, then a rails approach may be a possible solution. If it’s just to save some effort for personal ones then it’s likely not going to be the solution people are looking for.
But if it is, I’ll flip this to an #installation topic. 