Removal of CSS classes when uninstalled

I installed the Menu Icons module - nice, but didn't quite do what I needed for a particular design, so disabled and uninstalled it (and even removed files from modules directory).

However the classes it added to <a> tags (e.g. class="menu_icon menu-370") are still being generated and are still in the 'options' field of the {menu_links} table. No amount of clearing cache or calling menu_rebuild() (which is done in the module uninstall file) seems to clear these classes.

I'm particularly keen to remove them because I had some CSS that relied on them as selectors, but I didn't realise it until I added a new menu item, which didn't have the extra classes - causing confusion for a while!

Is this a general problem with the core menu module or something which menu_icon should be able to clear during uninstall?

What's the cleanest way to remove these manually, e.g. update the 'options' field to 'a:0:{}' in the {menu_links} table?