You can delete individual bookmarks, yes.. by touch/hold & sliding them to the right, revealing the individual 'Delete/cancel' option buttons 'underneath'.
They go into Bookmarks in the same order in which you dial them up.. so first in, is at the bottom of the list.
All I can think of, is for you to first dial up your desired web sites (from your Bookmarks) and save them also under 'Favourites' tab in the Launcher too, (by tapping the little square with the arrow sticking out of it at the top RH of your browser page open on the site in question and then tapping 'Add to launcher') then delete all your Bookmarks in the browser, then REdial them via the already saved 'Favourites' in the launcher, but in the reverse order in which you wish to then save them and for them to then reappear in your bookmarks.. ie. last dialed appearing at the top of your Bookmark list therefore.
I hope that is clear.. the thought has only just occurred to me as a result of your question!
Long-way-workaround.. but it should at least get you what you want, in the order in which you want them, in your Bookmark list anyway!
I actually have developed the habit now of not using 'Bookmarks'.. but saved 'Favorites' in the launcher tab anyway.. easier to scan a whole apps page for your site then scrolling down the B'mark list.. and also you can easily re-arrange the ordering in the Favorites tab by holding on an icon until it becomes 'moveable'!