OS X :: Deleting Sticky Note From Pdf In Preview

Recently found out that there is a really cool feature when reading pdf files in preview. You can add notes, that show in a side column. in the file itself, it shows just a little yellow square that looks like a dialogue box from a cartoon, but yellow in side with lines (ie: a reminder that there is a note attached) To me, when reading professional articles I've downloaded, it's a great feature. It's just like making notes in an article, or on sticky notes, but it's all stored in one place, with the article's pdf file. My question (and perhaps there will turn out to be a simple answer I've overlooked) is: How do you delete one of these notes if you don't want it anymore? I've tried everything I can think of, and can't figure it out.