$('li > a:contains("blabla")').remove();
Have a look at the :contains selector.
I've just noticed that :contains does partial matching. You may need to do...
$('li > a:contains("blabla")').each(function() {
if ($(this).text() === 'blabla') {
$(this).parent().remove();
}
});
You could also make the selector less strict if doing it that way.
... or you could do it much neater like Nick Craver.